Expansion Joint / Loop Guide Spacing (EJMA 4D/14D)
Where the first two guides go so an expansion joint or loop compresses instead of buckling sideways: the first guide within four pipe diameters of the joint, the second within fourteen diameters of the first, per the Expansion Joint Manufacturers Association (EJMA) rule. A 4 in line (OD 4.5) guides at 18 in then 63 in past it (81 in from the joint); the distances scale directly with the diameter, the multipliers are the fixed rule. Beyond guide 2 the intermediate spacing comes from the EJMA table or the pipe-column stability calc. This places the planning guides; the anchor and joint selection govern.
Formula and source
first_guide = d1_mult x pipe_od (default 4 diameters from the joint); second_guide = d2_mult x pipe_od (default 14 diameters past the first guide); guide 2 is first_guide + second_guide from the joint.
The Expansion Joint Manufacturers Association (EJMA) 4-diameter / 14-diameter guide-placement rule and the manufacturer installation guides, by name.
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