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Scaffold Components

Can Scaffolds Support This?

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Spring is in the air, the birds are chirping and scaffolds are being built. Can life get any better? It used to be that contractors feared winter in the northern regions of North America. Cold temperatures, snow, wind and generally miserable conditions prompted owners and contractors to curtail outdoor activities. That was then; now construction charges ahead, fearless and courageous against even the nastiest of weather. Once again science and progress has prevailed! Improved, clothing, materials, equipment and methods allow construction to continue in any environment.

 To facilitate these activities, it was common to enclose supported scaffolds against the weather. But times have changed; cold weather isn’t the only reason to enclose scaffolds. Containment of debris, tools and workers are now common reasons to enclose scaffolds. Enclosures are also used to advertise, block the work activities from pedestrians and even hide the workers who might be gawking at the pedestrians. Enclosing supported scaffolds is now a year around activity in all areas of North America, on all types of projects in all types of conditions.

Unfortunately, workers have false perceptions concerning supported scaffolds that are enclosed, including the perception that the forces on enclosed scaffolds are not as severe in summer as they are in winter; the perception that using open netting results in lower forces than using solid material; that no additional measures must be taken when a scaffold is enclosed and; site conditions have little effect on an enclosed scaffold.

The truth of the matter is that all scaffolds must be designed by a qualified person, that is, someone who can demonstrate the ability to properly design a scaffold, whether it is enclosed or not. Since designing for wind forces is a necessarily complicated matter, it is common that the qualified person for this design work is a Professional Engineer qualified in such activities. Of course, anyone can take a shot at the design (and unfortunately it is often the case), but the results can be fatal due to a gross underestimation of the forces developed by the wind. So, what is so complicated about wind design? Here are a few factors that must be considered:

Wind Forces

It is absolutely true that the force applied to a scaffold and its enclosure from the wind can be calculated. Short of a meteor falling out of the sky, there is no such thing as a “freak act of nature.” Those who argue so because their scaffold fell over need to be retrained. More accurately, an enclosed scaffold can be designed for a certain maximum wind speed; if the wind is expected to be higher than the design speed, either the scaffold must be dismantled, the enclosure removed, or additional measures must be taken to ensure the stability of the scaffold.

Wind Speed

Obviously, the wind velocity (speed) is the main factor in determining wind forces on a scaffold. However, choosing the correct wind speed for a specific location isn’t that easy. Although wind charts have been developed for North America that indicate maximum design wind velocities, choosing the correct velocity is just the starting point. In fact, there are numerous areas of the continent that have “special wind regions” that require additional investigation to determine the expected wind velocity. One example is along the east side of the Rocky Mountain range, extending from Montana down through Colorado and into New Mexico. At certain times of the year, Chinook winds, that is winds that drop down the east slopes of the mountains, reach as high as 100 mph. Similar winds, called the Santa Ana winds, occur in southern California. These winds don’t occur throughout the year; if your enclosed scaffold is erected during the right time of the year you don’t have to design for these winds; but watch out if the job is delayed and the scaffold is still standing when a Chinook wind hits!

Stability Ties

The key to scaffold success is to adequately design the scaffold and its connection to the adjacent structure. While U.S. federal OSHA and other agencies specify the minimum tie requirements for supported scaffolds, the tie spacing most likely will be grossly inadequate for any substantial enclosed scaffold. While #9 or #12 wire may suffice for a connection of an unenclosed scaffold, it typically is never adequate for an enclosed one. In other words, the ties for an enclosed scaffold must be designed for the anticipated tension and compression loads that are expected to occur. For those who choose to wing it and do something such as doubling up the ties should expect to see their scaffold take wing and fly like a kite. Keep in mind that it is not uncommon to have ties (and the adjacent structure) designed to hold several thousand pounds or more.

Adjustment Factors

When a qualified person designs an enclosed scaffold, he or she must consider these factors:

  • The height of the scaffold
  • The geographical location of the scaffold
  • The location of the scaffold relative to the surrounding structures
  • Surrounding Structures
  • Shape of the Scaffold/Structure (e.g. round or square)
  • Local Wind History
  • Partial or Full Enclosure
  • New construction or demolition
  • Existing structures—are the windows open or closed?

Time of year

This is not a complete list but it gives an idea of the potential complexity of the analysis and design.

Enclosure Porosity

Porosity is the fancy word for how many and how big are the holes in your enclosure material. If you are using netting, the holes can be quite small or they can be big. If the holes are over 2 inches in diameter, such as plastic fencing, porosity can be considered. Otherwise, the prudent scaffold designer will consider the netting as a solid material for the simple reason that the holes can become plugged. Snow and ice can easily plug the most porous netting in winter while sawdust, sand, asbestos (why you would use netting to try to contain asbestos is the more important question – you really need retraining!), stucco, plaster and other fine materials will also have an adverse effect on the airiness of your material regardless of the time of year.

While this article doesn’t cover all the factors that must be considered by the qualified person when designing an enclosed scaffold, it offers a glimpse into the complexity of the situation. Merely “doubling up the ties” and “this is the way I have always done it” is not a prudent approach; it just shows you are lucky. And while being lucky may work in craps or roulette, it has no place in the design of an enclosed supported scaffold. Is your life worth a throw of the dice?

Is it Okay or Not?

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How to determine if the scaffolding you have is in good condition or whether it should be scrapped.

Is your scaffold any good or has it seen better days?  While it would be nice to always use fresh out of the box (so to speak) scaffolding, the reality is quite different.  Scaffold components are used for many years, showing their age with each succeeding season.  How bad can the equipment get before it isn’t any good anymore?  How much rust is permissible?  How many dents and dings can we tolerate before it’s time to pitch it in the dumpster?

Since scaffolding isn’t free, although some suppliers may think they are giving it away, it is important that scaffold parts are not discarded before their useful life has ended.  After all, parts is parts.  On the other hand, it would not be prudent to use scaffolding that cannot function as expected.  What exactly determines whether a scaffold component is no longer useable?  For some components the answer is easy.  If a suspension rope has too many broken wire strands it’s time to throw it out.  If a suspension hoist has worn internal parts, it’s time to replace them.  If the motor doesn’t run, it should be obvious that something needs to be repaired.  But what about more subtle problems such as rust; how much rust is too much?  Should a scaffold frame, for example, be discarded because it has a rusty appearance or should it be kept in inventory, and rented, until the rust goes all the way through the tube wall? To answer those questions, it is best to understand what the hazards are.

Strength, fit, and alignment can be used to determine the worthiness of a scaffold component.  Strength is affected by a variety of factors.  For example, a cracked stirrup on a two point suspended scaffold would not be good.  Is it necessary to say that maintaining scaffold component strength is important to the integrity of the completed scaffold?  Well it is.  Consequently, any condition that affects the strength of the component is not allowed.  So, what precisely gives a scaffold its strength?  Let’s take a look at a supported scaffold, a scaffold that utilizes tubes for vertical support. The material that is used for the tube is one parameter that dictates strength.  Any action that adversely affects the properties of that material is not good.  For example, excessive heat will affect the molecular strength of the steel and therefore must be avoided.  The shape of the tube is important.  Any action that changes the shape of the tube will adversely affect the carrying capacity of the tube and therefore must be avoided.  This includes kinks, bends, distortion, flattening and stretching of the tube.

Decreasing dimensional changes in the tube wall thickness can never be a good thing.  This typically occurs through rust and corrosion although it can also happen through chemical deterioration (such as acids) and through galvanic/electrolytic action.  The question of course is how much corrosion is too much?  It should be obvious that if you can look through the wall of the tube and see daylight on the other side, you have a problem.  Basically the concern is whether the tube has lost too much of its material.  Surface rust is harmless.  Pitted surfaces are another story.  It is difficult to get complete consensus on the amount of pitting a tube can experience because evaluation is rather subjective.  Additionally, scaffold tube wall thickness varies depending on the type of scaffolding.  The wall thickness can be as little as 0.09 inches (2.3 mm or 3/32”) to more than 0.154 inches (3.91 mm or 5/32”).  If you have 1/32” (0.8 mm) pitting on a tube that has a wall thickness of 0.09” (2.3 mm) and you just lost a third of its material.  On the other hand, if you have a tube wall that is ¼” (6.35 mm) thick, you just lost 1/8 of its material.  It looks like the amount of permissible corrosion is based on the dimensional properties of the tube in question.  You may want to consult a metallurgist if a large inventory is under suspicion.

Dents and kinks in tubing decrease the strength of the component.  While a flattened horizontal tube in a scaffold frame will decrease the capacity it isn’t that big a deal if it is not the load bearing top ledger.  On the other hand, if the dent is in the leg or top ledger it can be a problem since it reduces the strength.  It’s tough to determine how much a dent decreases the capacity; don’t take a chance, discard it.  Kinks will most certainly decrease the capacity of a tube besides throwing the tube out of alignment.  Kinks in load bearing members mean discard it unless you have a qualified engineer analyze its worthiness.

Cracked welds are an indication of poor manufacturing or abuse.  In either case the component should be discarded unless a qualified and certified welder makes the repairs.  (Depending on the pay scale, it may be cheaper to get rid of the part.)  Broken welds surely indicate that the component was treated badly unless you bought the item from an unscrupulous dealer in the first place.  In any event, the component must be carefully examined for additional damage that was done to cause the weld to break in the first place.  If there is rust in the crack or break, this may be an indication of a pre-existing condition, which suggests that someone wasn’t taking care of the product and wasn’t examining it very closely in previous inspections.

Speaking of abuse, splits in tubes can never be good.  Splits can occur because of poor manufacturing or because someone tried to fit one leg on top of a larger diameter leg.  In either case, the tube is useless and must be discarded.  Twisted tubing, while rare, will overstress the material and degrade its strength.  Get rid of it.  This goes for twisted angles too.

Overall fit and alignment of members are important.  Taking a scaffold frame as an example, if it is racked (one leg is higher than the other) or warped (it doesn’t lie flat on the floor) you have a problem.  If the frame can be straightened without breaking the welds, go for it.  On the other hand, if you bought an inferior product, it may have been manufactured that way and you are out of luck.  You will never get the scaffold to be “plumb, level and square” as required by the regulations; you should have bought better stuff.

Look for missing appurtenances such as cross brace locks, wedges, pins, chains and bolts.  Make sure the bolts and pins are the correct size and have not been changed to bolts and pins of lesser strength or size.  Inspect critical items very carefully.  If the item is bent, it may also be cracked.  Don’t take chances.

Finally your manufacturer may have guidelines for inspection of their specific products.  It would be worth your while to contact them since they should know their products.  Also, go towww.ssfi.org for technical bulletins that will be of value to you.

Note:  Thanks to SAIA member Alan Kline for his suggestion for this month’s subject.

How Does the Scaffold Hold That Load?

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The OSHA standards require a scaffold user to have training. One of the requirements of that training is that the user must know “The maximum intended load and the load carrying capacities of the scaffold used” [29 CFR 1926.454(a)(4)].  (In case you are wondering, erectors are suppose to know this too.)  So, where do you find that information?  The manufacturer should have that information.  And the manufacturer gets that information either by testing the scaffold, that is load the scaffold until it fails, or by engineering analysis.  And how is it that a scaffold can support a load?  I have explained this before but it has been a long time so here it is again.

Have you ever wondered why a scaffold can support loads?  Have you ever wondered how an engineer can determine what a scaffold leg can support?  Do you wonder who thought up the way to answer those questions?  Wonder no more.  Thanks to Swiss physicist Leonhard Euler, (typically pronounced “Oiler”), a method was developed to determine the strength of a column (which is what a scaffold leg is). Back in 1774, Mr. Euler discovered that a column would not buckle until the load reached a certain amount.  This load, known both as the critical force and also as Euler’s Load, is affected by certain characteristics of the column.  These characteristics include the support conditions at the end of the column, the distance, or length, between support points, the shape of the column, and the material of the column.  Based on these parameters, Mr. Euler developed a formula that determined the critical load.

While scaffolds can be manufactured using a variety of materials, steel is the most common material used.  (Euler’s equation can be used with any material, including aluminum, fiberglass, plastic, and wood.)  Scaffolding is typically constructed with round tube, which is equally strong in all directions.  Second to a round tube is a square tube which exhibits similar qualities.  Rectangular tube may be used but the strength will be higher in the direction of the long face of the tube compared to the short face.  Other shapes may be used if the manufacturer determines that there may be an advantage.  While the shape of the material, and the material itself will help determine the capacity of a particular scaffold leg load, the characteristic that affects the strength of scaffolds more than the material or shape is the distance between points of support.  Depending on the scaffold type, these points of support may be cross braces, diagonal braces, horizontal braces, or ties to an existing substantial structure.  For example, in a tube and coupler scaffold, the length between points of support is usually 6’-6”.  The horizontal members and the diagonal members are connected to the legs at these intervals.  Therefore the length of the scaffold leg (column) is 6’-6”.  For a systems scaffold, the support points will occur where the horizontal and diagonal members are attached to the leg.  This usually occurs at 6’-6” to 7’-0”, similar to a tube and coupler scaffold.  A frame scaffold, on the other hand, will have points of support at the cross brace studs in one direction, and at the location of the horizontal members that are welded to the legs in the other direction.

The distance between the points of support is critical to the strength of the scaffold leg.  Reducing the distance between the horizontal members on a tube and coupler scaffold or systems scaffold by 50 per cent can more than double the strength of the scaffold leg.  Conversely, increasing the distance between horizontal members by 50 per cent, (not recommended,) can reduce the capacity by substantially more than 50 per cent.  Therefore, if one is to deviate from the standard erection procedures, it is important to verify the design prior to construction. Similarly, removing a critical cross brace from a frame scaffold can drastically reduce the capacity of the scaffold.  This is not to say that braces cannot be removed. A frame scaffold will have sufficient bracing as long as the scaffold leg is braced to at least one other leg.  However, removing the incorrect brace may result in a scaffold that is unable to provide the anticipated support.  This is not good!

Frame scaffolds also differ from tube and coupler, systems, and wood pole scaffolds in another aspect in that additional bracing is provided by the horizontal members that are welded into the frame.  Since this bracing varies between frame styles and manufacturers, all frames are not equal in capacity.  In fact, a review of scaffold load charts will show that frame capacities vary dramatically, depending on the height of the frame, the location and spacing of the brace studs, and the pattern of the frame horizontal members.

Mr. Euler’s formula has been used successfully for quite a long time.  Other formulae have been developed since Mr. Euler’s work and refinements have been made to these formulae so engineers can accurately predict the capacities of columns under a broad range of circumstances.  But keep in mind that the basic premise is still accurate: The capacity of a scaffold leg can be easily affected by modification of the distance between support points.  If you cannot accurately determine the effects these modifications will make, don’t modify the scaffold.  In other words, don’t mess with Mr. Euler’s formula!

Industrial or Commercial?

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Is it an industrial scaffold or a commercial scaffold?  That is the question that I am regularly asked.  And what is the answer?  Simply stated, I doubt there is a difference.  Now, before you industrial erectors get in a tizzy, there is no doubt that there is a difference in the application of the scaffold and the circumstances and environment where an industrial scaffold is used.  However, the physics, engineering, and safety are all the same.

So, is there a difference between industrial scaffolds, commercial scaffolds, and we may as well add maintenance scaffolds to the discussion?  I dare say that there is a difference.  Here is why I think so.  An industrial scaffold is normally used by trades that may never see a commercial project.  And so it is also true for commercial project scaffold users.  For example, I don’t think I have ever seen a stucco contractor working in an oil refinery.  But, on the other hand, I have seen a pipe fitter working in both a power plant and a high rise office building.  What makes the scaffold in each purpose different isn’t in the type of equipment but rather in its application to the specific situation.  Typically, systems scaffolds and tube & coupler scaffolds are a common sight at a refinery because these scaffolds provide the most versatility in reaching the desired location and elevation.  Conversely, frame scaffolds are the most common scaffolds on commercial sites because the congestion is so much less.  This is not to say the systems scaffolds are not seen on commercial sites; typically they are used on commercial sites due to their increased strength over frame scaffolds.  It is also true with tube & coupler scaffolds; you will find this equipment on commercial sites as auxiliary equipment that provides additional bracing for the primary scaffold.

The real difference, in my opinion, is in the procedural controls that have long been established at industrial projects that now are slowly expanding onto commercial projects.  The first example is the use of a tagging system.  As far as I know, this system began in refineries, chemical plants, power plants and other similar facilities.  It is based on a very tight control over the procedures that are in place at the facility.  And the tagging system works because of the tight controls.  Typically, the scaffold erector in an industrial plant also is responsible for the pre-workshift inspection of the scaffold.  Users of the scaffolds, besides having the training to recognize safety hazards on scaffolds, respect the tag and have been trained that if the tag is not current, the scaffold is not to be used.  Furthermore, the users understand that they (the users) shall not modify the scaffold; that task is left to the authorized trained and experienced workers charged with that work. And, obviously, if the tag is red the scaffold should not be used.  These kinds of controls, based on my experience, rarely exist on a commercial scaffold.

Another area where industrial scaffolds differ from commercial scaffolds is the platform.  The tendency at industrial facilities is to cover all openings in platforms with plywood, specifically the gaps that occur at scaffold legs and stairways.  Although the standards allow for these types of openings, industrial scaffold users prefer to have the gaps covered.  Such is not the case on many commercial sites where the gap between the main scaffold platform and say, the cantilever platform on the side brackets, is accepted and typical.  Next, due to the congestion at refineries, it is not uncommon to see multiple small platforms on a given scaffold.  Many of these platforms will be as small as 2 or 3 feet by 4 or 5 feet while on commercial sites the platform can be continuous along the entire face of the structure.

Access is another area where there is a difference, more because of the type of scaffold equipment being used than any other reason.  Since systems scaffolds are so prevalent in industrial environments, an attachable ladder is required (unless stairs are being used).  On commercial sites, where frame scaffolds are used, ladders will be omitted if the frame can be used for access.

Falling object protection is also addressed differently between commercial and industrial applications.  It is common for toeboards to be installed on all industrial scaffold platforms while commercial scaffolds may utilize alternative means of falling object protection including canopies and catch platforms.  Screens and barricades are common to both types of projects.

Finally, fall protection has notable differences between industrial and commercial scaffolds although there seems to be a merging of concepts in this regard.  It has been common in some industrial locations that all scaffold users utilize both guardrails and personal fall arrest equipment.  More importantly, scaffold erectors have been required to utilize personal fall protection, or at least “hook off” 100 per cent of the time.  That policy has now been adopted by general contractors in the commercial construction industry and we will see more companies insisting on 100 per cent tie off whether it is effective or not and despite it may not comply with the applicable standards and regulations.

So, as you can see, the scaffold is the same; it is only the application of the scaffold to meet the requirements of the customer and the restrictions of the site that makes industrial scaffolds different from a commercial scaffold.  Let’s face it—an injury or death is still an injury or death.  It doesn’t matter what type of scaffold it is; the scaffold has to be erected and used correctly no matter where it is.

We Still Have Rules

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However, recent accidents would indicate that something isn’t quite right.  Maybe the rules aren’t being followed.  Maybe somebody doesn’t know what he/she is doing.  Maybe it’s just plain old bad luck.  I’ll agree with the first two possibilities but most certainly not the third.  Scaffold construction is not a game of chance although some might think otherwise, especially considering recent disasters.

Each time a scaffold failure occurs, there’s a strong possibility that somebody broke a rule.  But it’s not the rule or following the rule that guarantees success.  It is following the principle or action described by the rule that guarantees success.  For example, bracing is required on all scaffolds.  The bracing stabilizes the scaffold and ensures significant strength.  Removing one brace component may or may not adversely affect the scaffold.  If the construction of the scaffold is not understood, that brace may cause a disaster.  Consequently there is a rule that requires that scaffold modification be done only under the supervision of a competent person.  Could the lack of supervision been the cause of recent scaffold accidents?

Not following the rules is a result of either not understanding the rules or choosing not to follow them.  Focusing on the first possibility, not understanding the rules, might be excusable were it not for a rule established in 1970 that every employer and employee must follow the rules, in this particular case, the Occupational Health and Safety (OASHA) Standards.  You, as a user, erector, supplier, manufacturer, or designer,  must know the rules before you get on a scaffold.  No exceptions allowed.  Choosing not to follow the rules, on the other hand, appears to be a sure fire route to disaster.  But is it?  What’s more important, following the letter  of the rule, or theintent of the rule.  No doubt the intent of the rule is the better route.  Unfortunately, to make that determination, you have to understand the purpose of the rule.  To arbitrarily not follow the rule, the minimum standard if you will, makes you directly responsible for your actions.  Are you ready to accept that responsibility?

Unfortunately, many workers view the OSHA Standards as a set of instructions, which they are not; they’re minimum standards, or simply put, rules!  Many workers also think that these rules are optional.  Consequently the unlevel playing field results, the complaints about unfair competition arises, and unequal enforcement of the rules occurs.  But think about it for a minute.  What would happen if their were no rules, no minimum standards for the scaffold industry?  Would you climb a scaffold constructed under those conditions?  Would you still complain about the rules?  I think not.

As an experiment, take a look at the rules for supported scaffolds, a temporary platform supported by rigid supports such as tubes and uprights.  Pick one, any one, and think about the basis for the rule, in other words the intent of that rule.  Does it make sense?  Do you apply the intent of that rule on your scaffolds?  If not, why not?  If so, why?  As an alternative, take a look at the scaffold you are about to use, or erect.  How many rules apply to this specific scaffold?  Could you construct or use this scaffold if it were not complying with any of the rules?  Would you want to use this scaffold if it were not in compliance?  The results of such an inspection might surprise you.  Perhaps the playing field is level after all.

This article was first written and published in 1998, more than 10 years ago.  It is still applicable today, and amazingly – after 10 years – scaffold users are still not complying with the rules!

That Time of Year

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It is not a healthy or a safe thing when scaffolds fall over.  Consequently, and not surprisingly, there are codes and standards that address scaffold stability and the minimum expectations regarding scaffold stability.  Both OSHA and ANSI, the American National Standards Institute, have minimum standards for the stability of scaffolds.  Simply stated, scaffolds must be secured to an existing substantial structure to make sure they don’t fall over.  While both agencies specify that the connections, or ties, be spaced no further apart than 26 feet vertically and 30 feet horizontally, (20 feet by 30 for scaffolds 3 feet and narrower), the codes are silent regarding the strength or the expected load on the tie.  In some ways the codes are misleading in that they may imply to the untrained worker that the prescribed spacing is both the minimum and maximumspacing of the ties.  In other words, no matter whether the scaffold is wrapped in an enclosure or not, the spacing remains the same.  Such is not the case!

Scaffolds must be designed by a qualified person, basically an individual who knows what he/she is doing.  If the scaffold is going to be enclosed, the qualified person must be familiar with wind forces, velocity, and environmental effects, in addition to other factors.  Where the scaffold is located, the shape of the scaffold, the shape of the structure, whether you are in Chattanooga or Casper, the height of the scaffold, if the windows are open or not, if the scaffold is in the city center or suburbs, and the height of the structure and the scaffold, are all factors that must be considered.  This is not time for guesswork and yet that is exactly what occurs.

One classic approach is to “double up the ties.”  Fortunately this works for a lot of scaffolds, not because it is accurate but because the scaffold erector is lucky.  That’s right, lucky.  Believe it or not, the force on the scaffold can be accurately calculated.  Much research has been conducted by engineers to determine the force of the wind on structures.  Several years ago a horrific accident occurred inChicagowhere a suspended scaffold failed and fell to the street, killing innocent people.  The ensuing investigation determined the vertical force on the scaffold due to the wind was over 11,000 pounds!  This is serious stuff and yes, the forces can be calculated.

Lucky for the scaffold industry, compliance and safety workers generally cannot determine the forces on a wrapped scaffold and consequently cannot determine if an enclosed scaffold is at risk or not.  But this is changing.

pic16-that-time-of-year

Figure 1 illustrates a scaffold at the Air Force Academy that was wrapped.  That area ofColoradocan experience high winds, in excess of 100 mph.  That’s like a Category 2 hurricane.  Is it possible to design a scaffold that can resist this kind of wind?  Sure—look at Figure 1.  Was this scaffold designed on the fly by doubling up the ties and hoping for the best?  No, it was designed by a qualified person, who appropriately applied engineering principles that resulted in a safe design and successful installation.  The bottom line:  Comply with the applicable standards and good construction practice:  Have a qualified person design the scaffold and construct the scaffold according to that design.  (How about that, there are ANSI and OSHA standards that say exactly that.)  So, how much force does the wind exert?

clip_image0021-that-time-of-year

Figure 2 shows an example of the types of forces that can be expected.  Note how the pressure increases dramatically as the wind speed increases.  In other words, at low wind speeds there isn’t much load on the scaffold but as the wind velocity increases, the pressure or force increases much faster.  Notice what happens at 90 mph.  Based on a tie spacing of 26 feet by 30 feet, the load on that tie is 1,625 pounds for an open scaffold but when it is enclosed, that load goes to 22,000 pounds.  That cheap eyebolt you’re using to hold that wire tie just isn’t going to fare well.  You may say that you don’t get 90 mph winds.  While that may be true, you can easily get 50 mph wind gusts and of course, you only need one gust to ruin your day.

What about the second issue, the issue where OSHA considers the enclosure installation as not being a part of the scaffold erection?  This is a sensitive issue.  Basically, OSHA is claiming that the enclosure is not a structural part of the scaffold and thus is not part of the scaffold erection.  Therefore, fall protection, either a guardrail system or personal fall protection system, is required for the enclosure installers; the OSHA Subpart L fall protection standards, 29 CFR 1926.451(g) apply.  However, OSHA chooses to ignore the fact that if a structure is erected solely for the purpose of supporting an enclosure, it is not a scaffold in spite of the fact that scaffold components are used to support the enclosure.  By definition, a scaffold is a temporary elevated platform and it’s supporting structure, used to support workers or materials or both.  If there is no elevated platform, there is no scaffold; the structure is a structure.  OSHA Subpart M would apply in this case.  What do we do?  Stay tuned, we’re working on it.

 

Still Developing?

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One new development is in the manufacturing of scaffolding components, particularly scaffold frames and systems scaffolds.  In the past, manufacturing has generally occurred inNorth Americafor most supported and suspended scaffold components used inNorth America.  Now, as with other manufactured products, most scaffold component production has shifted to countries with lower manufacturing costs.  Is this good for the industry or is it bad?  It depends on who you talk to. On the one hand, cheaper equipment costs mean better competition.  On the other hand, cheaper costs may suggest lack of quality.  (I wonder how manufacturing would have developed if OSHA, and others, had enforced 29 CFR 1926.451(a)(1) for the past 10 years.  That’s the regulation that says all scaffolds shall have a 4 to 1 safety factor, requiring the employer to know the strength of his/her scaffolding.

On a brighter note one promising development is in the relationship between the Scaffold Industry Association, SIA, and the US federal Occupational Safety & Health Administration, OSHA.  An alliance has been established between the two entities to promote access safety in the construction industry.  This alliance, a couple of years in the making, provides a common platform to share ideas and formulate strategies that will encourage better workplace practices for scaffold users.  This is another positive step in the evolution of access safety, an evolution that started with the establishment of both OSHA and the SIA in the 1970’s.

Another evolving development is the continuing growth of the SIA training program.  I had the opportunity to visit one of the training classes at the SIA Committee Week and it was a genuine pleasure to see the progress that has been made.  What an evolution this program has experienced since Committee Week inAlbuquerquein the mid ‘90’s when the concept was first proposed.  While it’s been a long road, the fruits of the labor are paying off handsomely.

A development that isn’t new but continues to manifest itself in clever and disturbing ways is the harassment of professional scaffold erectors concerning fall protection.  The extremely well written regulation regarding erector fall protection (29 CFR 1926.451(g)(2) is being abused, interpreted and mutilated, all cloaked in the sanctity of safety.  Let’s call this folly for what it is – a misunderstanding by misinformed individuals who haven’t worked in the shoes of an erector, perceiving that erectors, and by association the entire access/scaffold industry, just don’t care about safety.  This isn’t to say that the industry hasn’t dragged its’ collective feet in the past nor that all erectors are perfect.  However, based on my experience, this industry has invested more time, energy, money, and expertise in developing new strategies, products, knowledge and commitment to reduce the risks inherent with scaffold erection and use in the past decade than any other sector of the construction industry.  Unfortunately all this effort is being undermined by well meaning (I hope) but ill informed personnel who do not understand the bigger picture.  What a waste.  Professional erectors and professional scaffold companies are not the problem, they are the solution.

Enough of the negative thoughts.  Some (whoever they are) may think that a 70 year old product isn’t going to encourage new developments.  When put into perspective, scaffolding, whether its frame, system, suspended, aerial lifts or some derivative thereof, will continue to spawn new developments since access in construction will always be required.  It may be in the components or it may be in related areas such as engineering, assembly, inventory control, accounting or employee productivity.  We may not know what the development will be, but you can be sure there will be new development-look for it!

Promising Future

By | Aerial Lifts, Resources, Scaffold Components, Scaffolding | No Comments

One new development is in the manufacturing of scaffolding components, particularly scaffold frames and systems scaffolds.  In the past manufacturing has generally occurred in North America for most supported and suspended scaffold components used inNorth America.  Now, as with other manufactured products, most scaffold component production has shifted to countries with lower manufacturing costs.  Is this good for the industry or is it bad?  It depends on who you talk to. On the one hand, a cheaper equipment cost means better competition.  On the other hand, cheaper costs may suggest lack of quality.  (I wonder how manufacturing would have developed if OSHA, and others, had enforced 29 CFR 1926.451(a)(1) for the past 10 years.  That’s the regulation that says all scaffolds shall have a 4 to 1 safety factor, requiring the employer to know the strength of his/her scaffolding.)

On a brighter note one promising development is in the relationship between the Scaffold Industry Association, SIA, and the US federal Occupational Safety & Health Administration, OSHA.  An alliance has been established between the two entities to further access safety in the construction industry.  This alliance, a couple of years in the making, provides a common platform to share ideas and formulate strategies that will encourage better workplace practices for scaffold users.  This appears to be another step in the evolution of access safety, an evolution that started with the establishment of both OSHA and the SIA in the 1970’s.

Another evolving development is the continuing growth of the SIA training program.  I had the opportunity to visit one of the training classes at the SIA Committee Week and it was a genuine pleasure to see the progress that has been made.  What an evolution this program has experienced since Committee Week inAlbuquerquein the mid ‘90’s when the concept was first proposed.  While it’s been a long road, the fruits of the labor are paying off handsomely.

A development that isn’t new but continues to manifest itself in clever and disturbing ways is the harassment of professional scaffold erectors concerning fall protection.  The extremely well written regulation regarding erector fall protection (29 CFR 1926.451(g)(3) is being abused, interpreted and mutilated, all cloaked in the sanctity of safety.  Let’s call this folly for what it is – a misunderstanding by misinformed individuals who haven’t worked in the shoes of an erector, perceiving that erectors, and by association the entire access/scaffold industry, just don’t care about safety.  This isn’t to say that the industry hasn’t dragged its’ collective feet in the past nor that all erectors are perfect.  However, based on my experience, this industry has invested more time, energy, money, and expertise in developing new strategies, products, knowledge and commitment to reduce the risks inherent with scaffold erection and use in the past decade than any other sector of the construction industry.  Unfortunately all this effort is being undermined by well meaning (I hope) but ill informed personnel who do not understand the bigger picture.  What a waste.  Professional erectors and professional scaffold companies are not the problem, they are the solution.

Enough of the negative thoughts.  Some (whoever they are) may think that a 70 year old product isn’t going to encourage new developments.  When put into perspective, scaffolding, whether its frame, system, suspended, aerial lifts or some derivative thereof, will continue to spawn new developments since access in construction will always be required.  It may be in the components or it may be in related areas such as engineering, assembly, inventory control, accounting or employee productivity.  We may not know what the development will be, but you can be sure there will be new development-look for it!

Standard Applicability

By | Forming, Resources, Scaffold Components, Scaffolding Platforms | No Comments

Have you ever been asked if a scaffold is OSHA approved?  Or perhaps you have been asked if the scaffold is an “OSHA scaffold.”  When the question is asked, it has been my experience that the person really is asking if the scaffold in question complies with the applicable OSHA standards.  This begs the question:  What are the applicable standards?

If a scaffold is constructed of typical scaffold components, used for the support of a temporary elevated platform that supports workers and/or materials, the answer is straightforward.  But what happens if non-typical components are used, or if the structure isn’t a scaffold after all?  How do you determine what the applicable standards are?  How do you convince others of your evaluation.  While there are no standard procedures, here are the questions I ask to ascertain the correct application of standards, particularly when scaffold components are used in nontraditional ways.

  1. What is this structure being used for?  This is the basic question that seems so obvious but is often overlooked by safety evaluators.  Just because scaffold equipment is involved doesn’t guarantee that the structure is indeed a scaffold.  On the other hand, a scaffold can be constructed of virtually any type of material, possibly making the scaffold almost unrecognizable by typical standards.
  2. The applicable standards are…?  Once the structure is identified, the next step is to determine the standards that apply to the situation.  If it was decided the structure is a scaffold, then the scaffold standards would obviously apply.  If it has been determined that the structure is not a scaffold, then further evaluation is required to determine the applicable standards.
  3. This structure complies with the applicable standards because…?  Here is where the conversation may become lively.  Opinions will most certainly vary concerning what the standards mean.  Obviously, your opinion is correct and all others are wrong!  But how do you convince others of your wisdom?
  4. Ask the question:  “What is the intent of the assumed applicable standard?”  Here is where the trouble usually begins.  The tendency is to read only the letter of the standard without making the effort of understanding the purpose of the standard.  However, only by understanding the hazard that the standard is addressing (the intent) will you be successful in complying with the standards.
  5. Be honest with yourself.  Don’t try to make the standards fit the situation; rather make the situation fit the standards.  You don’t have the authority to make up standards or revise OSHA standards to justify your conclusions no matter how good you are.
  6. Verify compliance.  To fully ensure that the structure in question is constructed in compliance with the standards, thoroughly review all applicable standards.  If you aren’t satisfied that you have addressed all the hazards, ask for help from a qualified individual.  More importantly, if someone else questions the thoroughness, keep an open mind; that person may be more qualified and consequently may be right!

So, how does this really work?  Let’s try an example or two.  First, suppose we have three planks supported by two oil barrels.  There is a stepladder next to one of the barrels so the worker can access the platform.  What is this structure?  No scaffold frames, tube & clamp, or other standard scaffold products are involved.  Is this a scaffold?  Yes it is.  How do I know this?  The OSHA definition for a scaffold is that a scaffold is any temporary elevated platform, and its supporting structure, used to support workers or materials or both.  In this case the barrels support plank that support workers.  (Please don’t get excited and think I endorse this type of “scaffold.”  I use it for illustrative purposes only.)  In this example, the scaffold standards apply.

For example two, suppose you observe a trash chute that is thirty feet tall.  The chute is constructed of plywood supported by a rectangular structural tower constructed from frame scaffold components.  The plywood walls are inside the tower, forming a rectangular chute that is 5 feet wide, 7 feet long, and 30 feet high.  What is this structure?  Is it a scaffold?  Do the scaffold standards apply?  I think the scaffold standards do not apply.  While the chute is supported by a structure consisting of standard scaffold components, it is not being used to support an elevated temporary platform for workers or materials.  Therefore, by definition it is not a scaffold and Subpart L of the OSHA standards does not apply.  What standards do apply?  The demolition standards, Subpart XXXXXXXXXX probably apply.  General safety and health standards apply.  The OSHA General Duty Clause, which requires employers to provide a hazard free workplace, probably applies.  During the erection of the support tower (note that I did not say scaffold tower) the OSHA fall protection standards, Subpart M, apply.  Please remember that while the scaffold standards do not apply, it would be prudent to follow the manufacturer’s recommendations for the construction of the tower.

Scaffold systems are marvelous tools since they can be used in many innovative ways.

Can Hoists and Scaffolds Be Compatible?

By | Hoists, OSHA Standards & Regulations, Resources, Scaffold Components, Scaffolding | No Comments

Hoists and elevators are invaluable productivity enhancement devices used in project construction and renovation.  It would be impossible to complete today’s projects without hoists and elevators to move workers and materials vertically.  The Federal Occupational Safety and Health Administration, OSHA, and other agencies have standards that apply to the fabrication, installation, and use of hoists, elevators, and other similar devices.  However, understanding the standards that apply to the devices used to transport workers and materials is only a part of the picture.  Knowing how these devices interact with scaffold products is essential if safety is to be realized.

 

In a broad sense, vertical transport platforms can be generally classified in a manner similar to scaffolds.  The platforms can be supported by masts/columns or they can be supported by suspension ropes.  Within this broad categorization, many variants can be utilized to get the platform from the ground to where you want to go.  For example, an elevator in a 50 story building will be operated and supported by wire ropes while an elevator in a 2 story building will be operated by a hydraulic ram.  In other words, the one is supported by ropes while the other is supported by an adjustable column mounted on the lowest floor.  What does this have to do with scaffolding?  Well, nothing unless you decide to use the scaffold to support the hoist or elevator.  Then it can be pretty important to know what is going on.

 

Let’s look at mast supported hoists and elevators first. Keep in mind that there are very significant differences between material hoists and elevators used to transport humans.  However, the principle behind the operation of each is similar.  A mast or column supports the vertical load that is applied.  Depending on the design, the mast or column may also support the horizontal loads that will be applied to it.  What are these two loads?  The vertical load is the downward load that is a result of the weight of the car, the occupants, and the mast itself.  If this load is directly over the column or mast, there will be minimal horizontal loads.  On the other hand, if the car is cantilevered to the side of the mast, there can be a significant horizontal force that has to be restrained.  If the mast in question is attached to a building, for example, the hoist components, and the building, will restrain the forces.  If the mast however is attached to a scaffold, the scaffold had better be designed to handle those loads.  Since supported scaffolds are typically designed to support vertical loads only, a very qualified designer is required for these additional horizontal forces.  In fact, due to the potential complexity of the horizontal and vertical forces, some scaffold companies prohibit attaching large hoists and elevators to the scaffold.  This is not to say that it cannot be done; rather, these scaffold companies are very concerned about safe scaffold/hoist installation and use.

 

What about small hoists that transport material, such as scaffold components.  Can they be attached to scaffolds?  Sure, provided the scaffold is designed to support both the vertical and horizontal loads that will be imposed, not only by the hoist, but also by the materials that are being transported.  Impact loads also require consideration as the sudden starting and stopping of the machine can have an adverse effect on the ability of the scaffold to withstand the stresses.  If the hoist is mounted on the side of a scaffold tower the eccentric load caused by the hoist being outside the legs of the scaffold can produce significant forces that may exceed the capacity of the connection between the scaffold and the structure, resulting in cataclysmic results.  Consequently, the qualified designer must carefully consider all the forces that will occur and design accordingly.

 

Hoist platforms supported by suspension ropes typically apply only a vertical load to the supporting tower or apparatus.  These loads must be supported by the scaffold legs and just as important, by the members that directly hold the suspension ropes.  Again, a qualified person must design the entire structure, considering the impact, live, and equipment weight in the design.  The suspension cables must be strong enough for the loads and must be rigged according to the manufacturer’s recommendations.  Access gates and guardrail systems must be carefully designed into the scaffold so that there are no open sides or ends of the scaffold deck when the hoist platform is absent.  Lighting and signaling may also be a necessary part of the installation.

 

Even simple hand operated hoists can be disastrous in untrained hands.  The most basic hoist involves a rope that goes through a pulley supported by an arm attached to a scaffold leg.  Since these hoists have a very low load rating, you would think nothing could go wrong.  Unfortunately, workers can experience unwelcome results if they haven’t been trained properly.  The first tell tale sign that all is not right is a bent hoist arm.  Somebody hasn’t been told the load limit!  Next, the operator (the guy on the ground pulling on the rope) is standing a substantial distance away from the hoist, creating a potentially destabilizing horizontal force on the scaffold.  As the worker pulls and pulls, the load gets higher and higher and the horizontal force gets bigger and bigger.  About that time, the scaffold falls over and everybody is surprised.  The real surprise is that everybody is surprised.

 

If you are going to hoist materials or people, and you want the scaffold to support it, make sure you consider all the forces or you may find your vertical travel quickly becoming horizontal travel!