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Uniform Codes Questions & Answers
Uniform Codes Questions & Answers 

Every week we will be including additional questions and informal UPC and UMC interpretations

I understand that for corrosion (electrolysis) to occur, dissimilar metals must be joined together and exposed to wet or damp conditions. The water is the catalyst for the corrosion process. Without the touching of water, steel and copper, there could not be a problem. Is it required to isolate copper piping from the steel hanger?

There is a possibility of either corrosion or electrolysis when a difference in potential exists between metals. Abrasive action caused by expansion, contraction, vibration, and the possibility of condensate generation, may result in a condition requiring some means of isolating the copper pipe from the steel hanger to prevent premature failure. For these reasons, Section 314.4 (2003/2006/2009) 313.4 (2012) 313.2 (2015) states, in part, "Piping shall be isolated from incompatible materials.

Can you clarify for us if a gas-fired steam table requires ventilation via a Type II hood?

Section 508.1 requires hoods above all commercial-type deep fat fryers, broilers, fry grills, steam-jacketed kettles, hot-top ranges, ovens, barbecues, rotisseries, dishwashing machines and similar equipment which produce comparable amounts of steam, smoke, grease or heat in food-processing establishments. The Authority Having Jurisdiction (AHJ) would have to determine if the piece of equipment produces a comparable amount of steam to warrant the installation of a Type II hood. There are several pieces of kitchen equipment available that produce varying amounts of steam. It would be difficult to say that all steam tables require a Type II hood, when there may not be enough steam escaping to be concerned. Additionally, most kitchen and restaurants move a tremendous amount of air that may be enough to compensate for small steam producing units. The decision to require a Type II hood would have to be made by the AHJ taking into account the amount of steam being produced by the equipment and the design of the air moving system serving the space.

Does Section 311.4 (2003/2006/2009),310.4 (2012/2015)expressly prohibit Single Stack Drainage and Venting Systems?

Section 311.4 (2003/2006/2009), 310.4 (2012/2015) prohibits the installation of "single stack drainage and venting systems with unvented branch lines " Section 301.2.2 (2003) 301.2 (2006/2009/2012) 301.3 (2015) states, "The Authority Having Jurisdiction may approve any such alternate provided that the Authority Having Jurisdiction finds that the proposed design is satisfactory and complies with the intent of this Code." It is the intent of this code that every trap be protected by a vent to guard "against siphonage and to ensure air circulation" throughout all parts of the drainage Section 1004.0 (2003/2006/2009/2012/2015) prohibits the use of "S" traps. None of these basic plumbing design provisions are possible when "unvented branch lines" are installed. In summary, modern waste and vent systems have evolved from the one pipe systems of the late 1800's because science and empirical evidence have shown what works and does not work well. Meeting the intent of the UPC and modern plumbing system design cannot be achieved by installing oversized, unvented "S" traps as an "alternative" system. Opting for such systems simply ignores standard plumbing concepts which have been developed and proven during the past 100 years.

Is the exhaust airstream from an enclosed parking garage to be considered “environmental air” or “product conveying air”?

The exhaust from an enclosed parking garage is considered product conveying air since these exhausts routinely convey exhaust products containing carbon monoxide and smoke. Additionally, since garage ventilation systems may also be required to dissipate fumes from vehicular fuel spills, it is recommended that they should be regarded as ducts conveying flammable vapors. See also UMC Answers and Analysis Section 506.9.1, Vent Termination.

When installing a floor sink, which an indirect waste from a commercial sink drains into, should the floor rim flange of the sink be placed on top of the finished floor or set flush with the finished floor?

The UPC does not require elevation of receptors to prevent the tops of their flanges from being flush with the finished floor. Nonetheless, specific conditions may justify local authorities requiring receptors to be installed as to prevent unintended waste collection from other than the intended primary fixture. See also 408.1 and 408.2 (2003) 407.1 and 407.2 (2006/2009) 402.0 (2012/2015)

Section 510.5.2.2 does not permit the use of a flanged with edge weld or flanged with filled weld. Would this method be allowed in the UMC as Figures 5-6 a, b, c, d clearly allow the use of a flanged connection that is no different than the welded flange?

No. The 2006 UMC only allows overlapping duct connections of either telescoping or bell type for welded field joints. The examples used in UMC Figure 5-6 (2003/2006/2009) are to be used only in a duct-to-fan connection. The reason for the limitation is to prevent pocketing of grease in the duct that could result in excessive accumulation of grease.

Do the standards listed in Table 14-1 of Chapter 14 constitute mandatory code requirements of jurisdictions adopting the UPC, or is their application optional at the discretion of the local Authority Having Jurisdiction?

The UPC formerly required that all plumbing components be submitted to the local Authority Having Jurisdiction for approval. Plumbing products also had to conform to the applicable standards of Table 14-1, Table 1401.1 (2012) Table 1701.1 (2015) To make the UPC eligible for local adoption by reference in many areas, three copies of each standard cited had to be made available to the adopting agency for its files. This became impractical because of the mass of supporting documents that was required to be submitted. Although these standards were being applied and met nationally, they were often unavailable and were commonly cross-referenced to other complementary standards. Section 301.1.1 (2003/2006/2009/2012) 301.2 (2015) requires that all plumbing materials “shall be submitted to the Authority Having Jurisdiction for approval and shall conform to approved applicable recognized standards and shall be free from defects.” This leaves the final acceptance of plumbing materials and the choice of standards strictly up to the local enforcement agency. The standards in Table 14-1, Table 1401.1 (2012) Table 1701.1 (2015) are, in most instances, the only nationally-recognized standards covering the subject item. They have been painstakingly developed by the plumbing industry and most of the plumbing components now in general use conform to one or more of these standards. The standards listed in Table 14-1, Table 1401.1 (2012) provide adequate guidelines by which to judge the acceptability of plumbing materials.

Does the UMC have jurisdiction over compressed air systems and compressed air piping? Or does ASME B31.1 have jurisdiction over pressure vessels and compressed air systems?

The UMC in conjunction with ASME B31.3 would apply. Chapter 14 (Process Piping), provides the provisions for piping conveying gases, while ASME B31.3 would provide the requirements for the remaining portion of a compressed air system. Since air is a gas, Chapter 14 would apply. If any conflicts arose the UMC would take precedence. The appropriate standard for pressure vessels would be ASME Boiler & Pressure Vessel Code Part VIII, Division 1, 2 or 3 based on the operating pressures.

In a gas piping system in a restaurant, is the ansul valve considered an appliance?

No. This valve would be more correctly defined as an appurtenance

Do all metal ducts buried in the ground need to be encased in concrete? There are no exceptions listed in Section 604.0 therefore should it be encased in concrete? Is the intent of this requirement to encase the pipe in concrete?

Yes, metal ducts when installed in or under concrete slab shall be encased in at least 2 inches of concrete. There are products approved for direct bury such as fiberglass, reinforced products and PVC coated metal ducts that do not have to be encased in concrete.

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