Valve Engineering
Specification Guides
Service-specific engineering guides for specifying and selecting industrial valves in demanding process conditions. Covers materials, standards, failure modes, and documentation requirements — written for plant engineers, project engineers, and technical procurement.
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Maintained by the Vajra Industrial Solutions Engineering Team
5
Specification Guides
Available Guides
Each guide covers failure modes, material requirements, applicable standards, key specification decisions, and documentation checklists for a specific service environment.
Sour Service Valve Specification
NACE MR0175 / ISO 15156 — H2S, Wet CO2, Sulphide Stress Cracking
- -Fluid qualifies as sour if H2S partial pressure exceeds 0.0003 MPa (0.3 mbar) in the gas phase — NACE MR0175 / ISO 15156 threshold
- -Maximum hardness: body and trim HRC 22 (Rockwell C) — 248 HV Vickers — prevents sulphide stress cracking (SSC)
- -Carbon steel (A216 WCB) is acceptable if PWHT applied and hardness controlled — confirm heat treatment records
Cryogenic Valve Specification
LNG, Liquid Nitrogen, Ethylene — Below -46°C / Extended Bonnet Requirements
- -Standard carbon steel (WCB) becomes brittle below -29°C — minimum temperature for WCB is -29°C as-cast, -46°C with impact testing
- -For LNG service (-162°C), use A351 CF8M (SS316) or A352 LC3 (3.5Ni steel) bodies with extended bonnet
- -Extended (cryogenic) bonnet required to keep packing at ambient temperature — prevents stem seal failure from thermal contraction
Steam Valve Selection Guide
Saturated & Superheated Steam — IBR, Pressure Seal, High-Temperature Materials
- -For steam above 300°C, use WC6 (1.25Cr-0.5Mo) or WC9 (2.25Cr-1Mo) body — standard WCB is acceptable only to 427°C but creep limits it practically to 300°C for prolonged service
- -Pressure seal bonnet (self-sealing under pressure) is standard for Class 600 and above gate and globe valves in steam service — bolted bonnet is not suitable above Class 600 for sustained high-temperature steam
- -IBR (Indian Boilers Regulation) certification required for steam service above 110°C and 1 kg/cm² — applies even to standard API valves installed in Indian boiler plant
Slurry Valve Selection Guide
Abrasive, Viscous, and Solids-Laden Flow — Wear, Erosion, and Blockage Prevention
- -Slurry service demands full-bore, self-cleaning valve designs — standard globe and gate valves trap solids and fail rapidly
- -Knife gate valves (API 594 / AWWA C520) are the primary isolation valve for slurries with solids content above 5% — the knife disc shears through the slurry when closing
- -Pinch valves provide the most erosion-resistant design — the rubber sleeve is the only wetted part, requires no metal-to-slurry contact, and replaceable sleeves eliminate maintenance cost
Oxygen Service Valve Requirements
Degreasing, Non-Sparking Materials, Fire-Safe Design — Clean Service Protocol
- -Oxygen service is one of the most hazardous in industrial applications — ignition of hydrocarbon contamination in high-pressure O2 is catastrophic and spontaneous
- -All valves for O2 service must be cleaned and degreased to oxygen-clean standard — zero hydrocarbon contamination (< 50 mg/m² non-volatile residue per EIGA IGC Doc 33)
- -Ball valves in high-pressure oxygen (> 40 bar) are generally NOT recommended — adiabatic compression ignition of particles can ignite the valve body
What Each Guide Covers
How to determine whether your process conditions trigger special requirements (H2S threshold, cryogenic temperature, oxygen purity, steam pressure).
The specific failure mechanisms that kill valves in each service — SSC, HIC, thermal shock, galling, autoignition, erosion — and how to prevent them.
Body, trim, seat, and packing material requirements with ASTM grades, hardness limits, and compatibility notes for each service environment.
Which standards govern design, testing, and certification for each service type — API, ASME, NACE, ISO, BS — with scope and applicability notes.
The 5–8 choices every engineer must make when specifying for this service: seat type, bonnet design, body configuration, testing requirements.
What paperwork is required at delivery — MTC grades, hardness surveys, test certificates, NACE compliance statements, third-party inspection records.
Related Engineering Tools
Input service conditions, get valve type + material + standard recommendations.
Generate a printable procurement spec sheet from your service data.
API 598 shell and seat test pressures for all pressure classes and materials.
ASME B16.34 pressure-temperature ratings by material group and pressure class.
Need Technical Support?
Our team supports specification review, material selection queries, and application-specific sourcing. Send your service conditions to sales@vajravyuh.com or submit a technical RFQ.