ASME B31.1 Section 107 / MSS SP-92
What it means on the job
This is a proper installation. Globe valves on steam service should be installed with flow entering under the disc to prevent the disc from being forced off the stem by line pressure when the valve is open. The vertical stem-up orientation is preferred for steam service to prevent condensate from pooling in the bonnet.
Tested in 2 CraftIQ puzzles
- whats-wrongValve Installation on Steam System
- code-checkValve Orientation
Related ASME sections
ASME B31.1 / ASHRAE Handbook — HVAC Systems
This is a textbook-correct steam trap installation as taught at UA halls. The F&T trap is appropriate for equipment drains (it handles variable condensate loads and passes air). The strainer upstream protects the trap internals from scale and debris. The check valve downstream prevents condensate backflow from the pressurized return header. Installing the trap at the same level as the drain (no lift) ensures gravity drainage into the trap — any lift before the trap creates a water seal that impedes condensate flow.
ASME B31.1 / Steam trap selection per Armstrong/Spirax Sarco
Steam heat exchangers must have properly functioning steam traps on the condensate outlet to remove condensate and prevent water hammer. Water hammer in steam systems generates pressure shocks up to 10 times operating pressure, which can rupture piping, damage equipment, and cause severe personnel injuries.
ASME B31.1 para. 131.4 (Table 132) / ASME BPVC Section IX
Carbon steel (P-No. 1 group) with a specified maximum carbon content over 0.30% AND a thickness at the joint over 1 inch requires a minimum mandatory preheat of 175°F before welding per ASME B31.1. Failure to preheat risks hydrogen cracking in the heat-affected zone.
ASME B31.1 Section 107.2
A check valve installed backwards blocks forward flow and allows reverse flow — the exact opposite of its purpose. Flow direction arrow must match the piping flow direction.
ASME B31.1 Section 114
ASME B31.1 requires welded or flanged connections for steam piping 2-1/2 inches and larger. Threaded connections on larger steam lines are prone to leaks under thermal expansion.
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.
CraftIQ explanations are original educational commentary written in trade language and verified against the cited standards. Always confirm requirements against the code edition adopted by your jurisdiction — this is training material, not a substitute for the code book or your AHJ.