Generally there are two issues that determine if scaffolds are compatible; the first issue applies to the same type of scaffold of different designs or manufactured by different manufacturers.  For example, a tubular welded frame scaffold manufactured by company A has a leg diameter of 1 inch while the tubular welded frame scaffold manufactured by company B has a leg diameter of 3 inches.  Obviously, the 1 inch diameter tube would not fit onto the 3 inch diameter leg.  This would make it incompatible.  The second issue applies to different types of scaffolds.  For example, can a tube & coupler scaffold, typically using tubes that are a nominal 2 inch diameter tube, be used with a systems scaffold that has the same diameter tube?  Can this same scaffold be used with a tubular welded frame scaffold that has a tube diameter of 1-5/8”?  These are legitimate questions for the scaffold inspector.

The Scaffold, Shoring & Forming Institute, SSFI, and manufacturers have guidelines about the matter.  So does the Scaffold Industry Association, (SIA).  The guidelines typically agree with the OSHA standards which succinctly sum it up:  “Scaffold components manufactured by different manufacturers shall not be modified in order to intermix them unless a competent person determines that the resulting scaffold is structurally sound.”  This means that scaffold components from different manufacturers can indeed by intermixed as long as the scaffold integrity is not compromised.

Here are factors that determine if seemingly different types of scaffolds are really compatible:

• What does the manufacturer have to say about it?
• Are the scaffolds the same type of scaffolds (e.g. systems scaffolds)?
• Are the scaffolds manufactured of the same material (e.g., steel)?
• Do the scaffolds fit together well? (although this isn’t a real good gauge of whether the scaffold is compatible since a really big hammer will solve this problem)

For tubular welded frame scaffolds, consider this:

• Are the tube diameters the same?
• Is the cross brace stud spacing the same?
• Is the distance from the top cross brace stud to the top of the frame the same?
• What is the height of the frame?  (A 5’-0” frame isn’t necessarily 5 feet tall)
• Does the coupling pin have a collar?
• If it does have a collar, is it the same height?  (Some coupling pins have no collar, some have an eighth or quarter inch collar and some have a one inch collar).
• Do the holes for the coupling pin retainer pins line up?
• Are the tube diameters the same?  Some tubes are 1.625” diameter (1-5/8”) and others are 1.69 inches.
• Is the steel the same type of steel?  Is it 36 ksi, 50 ksi, or stronger?
• If you know who the manufacturer is, what does he/she have to say about it?

For systems scaffolds, consider this:

• Are the connections compatible?  Most connection points (rosettes, node points, etc.) are proprietary but many “ring” type connections may be compatible.
• What is the spacing between connection points?  Most connections are a half meter (19.685 inches) but one systems scaffold connection spacing is 21 inches.
• Is the steel the same type of steel?  Is it 36 ksi, 50 ksi, or stronger?
• What is the tube diameter?
• If you know who the manufacturer is, what does he/she have to say about it?

For tube & coupler scaffolds, consider this:

• Are the couplers (clamps) compatible?
• Are the end fittings compatible?  (While the “bayonet” fittings may look alike, they do not necessarily lock together.)
• Is the steel the same type of steel?  Is it 36 ksi, 50 ksi, or stronger?
• What is the tube diameter?
• What is the tube wall thickness?
• Pipe is not the same as tube.  Are you specifying the correct product?
• Are the couplers sized for the tube being used?
• If you know who the manufacturer is, what does he/she have to say about it?

This isn’t meant to be a complete list since there are many manufacturers with many products.  The OSHA standards exist to ensure that intermixed equipment performs as anticipated.  By requiring an evaluation by a competent person, the scaffold user will have a safe scaffold to use.  If you are not comfortable determining the compatibility between scaffold components, manufacturers, materials, and scaffold types, don’t guess – contact a competent person and/or a competent/qualified manufacturer.