ASME B31.1 Section 137 / EJMA Standards

ASME B31.1 Section 119

The expansion loop is drastically undersized. The calculated thermal expansion is approximately 3.28 inches, but the loop is only designed for 1.4 inches of movement. This means the loop will be overstressed, potentially causing weld failures or equipment nozzle damage. The expansion device must be resized to handle the full calculated movement with appropriate safety factor per ASME B31.1.

ASME B31.1 Section 122 / ASHRAE Handbook

Condensate is highly corrosive (carbonic acid from CO2). Condensate return piping should be stainless steel, copper, or use Schedule 80 carbon steel with corrosion allowance. Standard weight carbon steel corrodes rapidly.

ASME B31.1 Section 127.4 / AWS D10.9

Undercut exceeding 1/32 inch (0.8 mm) on any weld is a rejectable defect per ASME B31.1 and AWS D10.9. Undercut creates a stress riser that can initiate fatigue cracking under thermal cycling.

ASME B31.1 Section 137.4

This is a proper hydrostatic test per ASME B31.1. The test pressure of 1.5 times design pressure (150 × 1.5 = 225 PSI) is correct. The 10-minute hold with visual inspection of all joints meets the minimum requirements. The system passes inspection.

ASME B31.3 §314.1(a) / §314.2.1

Threaded joints are a common leak path under vibration and thermal cycling, and a pump discharge sees both — ASME B31.3 para. 314.1(a) says threaded joints should be avoided where crevice corrosion, severe erosion or cyclic loading may occur, and 314.2.1 restricts them under severe cyclic conditions. Welded or flanged is the right call here. But do not carry away a size rule that does not exist: B31.3 sets NO NPS limit on threading, and ASME B16.11 lists threaded fittings through NPS 4. The "nothing threaded above 2 inch" cap most people quote comes from the project piping specification, not from the code. Where the code does address the lost wall thickness, it does it through the minimum schedule of Table 314.2.1 — a required wall, not a size ban.

ASME B31.3 §322.6.3 via ASME BPVC VIII UG-135(f)

Relief discharge piping must be arranged so backpressure does not impair the valve's relieving capacity. Reducing the discharge line raises backpressure, which raises the effective set pressure and can stop the valve relieving at all — the one device protecting the system becomes the device that has been disabled. ASME B31.3 §322.6.3 defers to ASME BPVC Section VIII UG-135(f) for discharge piping; the explicit full-area rule people quote is B31.1 §122.6.2, a different code book.