Crestline Mechanical Specifications

Crestline Mechanical Specification / ASTM C1136

PVC jacketing is not permitted on outdoor pipe insulation per Crestline specifications. PVC degrades under UV exposure, becomes brittle, and cracks, allowing moisture infiltration that destroys the insulation. Aluminum or stainless steel jacketing is required for outdoor applications.

Crestline Mechanical Specification / California T-24

This installation meets code. In Climate Zone 3, the minimum R-value for supply and return ducts located outside the building is R-8. The contractor correctly used DW-B insulation with a metal jacket, which is required for exterior duct applications to protect the insulation from weather, UV damage, and physical abuse. If this project were in Climate Zone 5 or higher, R-12 would be required instead of R-8.

Crestline Mechanical Specification / SMACNA

Duct liner is NOT allowed inside kitchen supply ducts, regardless of NRC rating or installation quality. Grease-laden air can saturate fiberglass liner, creating a fire hazard and breeding ground for bacteria. The Crestline spec explicitly prohibits internal duct liner on kitchen supply ductwork. Noise reduction in kitchen duct systems must be achieved through external duct wrap, sound attenuators, or duct silencers mounted upstream of the kitchen branch.

Crestline Mechanical Specifications / ASME B31.9

Ball valves are not permitted underground per the Crestline specifications. All underground valves must be gate valves. Gate valves are preferred underground because they provide a full-port opening with minimal pressure drop when fully open, and their rising stem or position indicator makes it easy to verify valve position from above the valve box. Ball valves underground are problematic because the handle position can be ambiguous through a valve box access, and ball valve seats can be damaged by debris common in underground installations. The ball valve must be replaced with a gate valve of the same size and pressure rating.

Crestline Mechanical Specifications / Site Plan

This installation is correct. Per the Crestline plans, all underground piping not directly outside the central plant is rated for 140 degrees F. The 180 degrees F rating is only required for piping immediately outside the central plant where water temperatures are highest. Building-to-building distribution piping at 140 degrees F rating is appropriate because water temperature drops through the distribution network. The 36" cover also meets the minimum burial depth requirement specified on the detail sheet.

Crestline Piping Specification / ASTM B88

Type M copper is NOT acceptable for pressure water piping per the project specification. Type M has the thinnest wall of the three copper tube types (K, L, M) and does not provide adequate long-term reliability for commercial pressure water service. Type L is the minimum required for above-ground pressure water piping, and Type K is required for underground or high-pressure applications. While Type M may be allowed by some residential codes, commercial specifications almost universally prohibit it for pressure service due to its susceptibility to erosion corrosion and pinhole leaks over time.