NFPA 13 goes on to define exactly how to comply with this “lesser degree” requirement, by listing five standard installation practices (1-5 below) that are generally accepted. This leaves the door open for what is defined as “other approved means” (option 6 below).**
1) Listed Sway Brace Assembly
2) Wraparound U-Hook satisfying the requirements of 188.8.131.52.11
3) No. 12, 440 lb. (200 kg) wire installed at least 45 degrees from the vertical plane and anchored on both sides of the pipe.
4) CPVC hangers utilizing two points of attachment
5) Hanger not less than 45 degrees from vertical installed within 6 in. (152 mm) of the vertical hanger arranged for restraint against upward movement, provided it is utilized such that l/r does not exceed 400, where the rod shall extend to the pipe or have a surge clip installed.
6) Other approved means
**Source; NFPA 13 (2013) Sec 184.108.40.206
At a glance, the first five practices seem straight forward, but what about the sixth? What are “other approved means?”
UL provides some insight to Authorities Having Jurisdiction (AHJ) on how to evaluate “other approved means" UL’s “Outline of Investigation for Sway Brace Devices (UL 203A; rev 6 15 2011)” includes a section that addresses products that meet a lesser degree of performance than those that achieve a listing as a lateral or longitudinal sway brace fitting or structural attachment. This creates a new “sub-section” for UL listing called a “Restraint Device.” Typically, these products will have loads in the range of approximately 300 lbs. or a lower l/r than its UL listed Sway Brace counterparts. The L/R or Slenderness Ratio refers to the allowable length of a rigid brace member. Limitations on length are imposed due to compressive force that acts on the branch line restraint assembly. Loads are affected by the length of the brace member of the branch line restraint. Simply stated, the longer the brace member is, the lower the ability to sustain a load.
However, there is a proposed word of caution regarding UL listed restraint devices. They are stamped with the UL logo and are shown in the same file as manufacturer-approved “Sway Brace” products, but are not UL listed to perform the same function.
Generally, these UL listed “Restraint” products should not be used to brace main or cross main piping. They should only be used as branch line restraints as their listing indicates. Recent changes to the UL test procedure have resulted in many manufacturers having products there were previously listed as a “Sway Brace” to fall into the new category of “Restraint”. This can create a problem when contractors install products that were previously UL listed as a lateral brace, but now are only listed as a restraint. If these products are installed for a purpose for which they are not listed, it is the same as installing a non-listed product. AHJ should be aware of the latest UL listings during both the plan review and inspection processes.