Valves

Module from the Piping Engineering Curriculum curriculum.

Module 6 — Valve Selection & Application · Learning Objectives · 1. Select isolation, throttling, and check valves for common services · 2. Apply API 600 / API 602 / API 608 / API 609 valve standards · 3. Identify fire-safe requirements per API 607 / API 6FA · 4. Understand trim material selection (CA15, 410, 316, Stellite, Alloy 6) · 5. Recognize when to require SIL-rated actuated valves (IEC 61508/61511) · Valve Type Selection by Function

Function	Best Choice	Alternate	Avoid	Standard	Notes
On-off isolation (liquid/gas)	Gate (OS&Y)	Ball (trunnion)	Globe	API 600 / API 608	Low ΔP open
Throttling / control	Globe	Segmented ball	Gate	API 623	Higher ΔP, trim wear
Slurry / dirty	Knife gate or ball	Plug	Globe	MSS SP-81	Avoid seat clogging
Double-block-and-bleed	DBB ball	Two gates + bleed	Single seal	API 6D	For safe isolation
Check (reverse flow)	Swing check	Dual-plate, piston	Lift check on vertical	API 594	Vertical = lift
Large line low-P isolation	Butterfly	Gate	Globe	API 609	Cost-effective > NPS 12
Fire-safe emergency isolation	Firesafe ball	Fire-tested gate	Soft-seat only	API 607 / 6FA	Graphite secondary
Cryogenic service	Extended-bonnet gate	Extended-bonnet ball	Standard	BS 6364	Protect stem packing
High purity / drainable	Diaphragm	Sanitary ball	Gate	BPE	Smooth ID
Common Valve Trim Materials
Trim	Seat	Disc/Ball	Stem	Service Limit	Notes
Trim 5	13Cr (CA15)	13Cr	13Cr	< 800 °F	Standard oil & gas
Trim 8	13Cr / Stellite	Stellite hardface	13Cr	< 1000 °F	Higher wear resistance
Trim 10	316 / 316	316	316	Corrosive	SS trim
Trim 12	Alloy 6 hardface	Alloy 6	316	Severe	Best erosion
Trim 16	CA15 + Alloy 6	CA15 + Alloy 6	13Cr	High temp wet H2S	NACE compliant
Monel	Monel	Monel	Monel	HF acid	Alkylation

Source: Piping_Engineering_Curriculum_v1.xlsx · Sheet: Valves

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