Alloy Steel Valves · WC6 · WC9 · Cr-Mo · Saudi Arabia · SAEP-347

Alloy Steel Valves Saudi Arabia — ASTM A217 WC6, WC9 for High-Temperature Refinery Service

API 600 Gate Valves · API 6D Ball Valves · WC6 · WC9 · Class 150–2500 · SAEP-347 · EN 10204 3.1

Gulf Union Ozone supplies alloy steel valves in ASTM A217 WC6 and WC9 chrome-moly for Saudi Aramco refinery units, gas processing plants, and high-temperature process piping across Saudi Arabia. WC6 and WC9 alloy steel is specified when service temperature exceeds 425 °C — the upper limit for carbon steel A216 WCB — covering crude distillation units (CDU), vacuum units (VDU), hydrotreaters, and hydrogen service where chromium-molybdenum steel provides the required creep strength and oxidation resistance. All valves are supplied with EN 10204 3.1 Mill Test Certificates confirming ASTM A217 chemical composition and mechanical properties.

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Alloy steel valves WC6 WC9 Saudi Arabia API 600 SAEP-347 high temperature refinery — Gulf Union Ozone Jeddah
MaterialA217 WC6 · WC9
Alloy1¼Cr-½Mo · 2¼Cr-1Mo
Max Temp595 °C (1100 °F)
MTCsEN 10204 Type 3.1
StandardsAPI 600 · API 6D
SAEP-347Annex 4 Compatible
Why Alloy Steel?

WC6 and WC9 — When Carbon Steel Is Not Enough

Carbon steel ASTM A216 WCB is the standard body material for general-purpose industrial valves — suitable for temperatures up to 425 °C and a wide range of non-corrosive process fluids. However, refinery applications routinely operate above this limit: crude distillation overhead temperatures of 340–370 °C, atmospheric residue service at 360–390 °C, vacuum residue at 400–420 °C, and furnace outlet and hydrotreater reactor lines at 450–540 °C. At these temperatures, carbon steel approaches or exceeds its safe creep rupture limit, making alloy steel the required specification.

ASTM A217 WC6 (1¼Cr-½Mo) and WC9 (2¼Cr-1Mo) extend the service temperature ceiling to 595 °C continuous. The chromium content improves oxidation resistance, while molybdenum stabilizes the carbide structure to prevent carbon migration (graphitisation) at elevated temperature — a known failure mode for plain carbon steel at sustained temperatures above 430 °C. WC9 with its higher Cr-Mo content is further specified for hydrogen service (H₂ partial pressure environments) in hydrotreaters and hydrocrackers, where WC6 may be insufficient at high H₂ partial pressure depending on the Nelson Curve limits.

In Summary

WC6 is the standard alloy steel specification for high-temperature steam and hydrocarbon service above 425 °C in most Saudi Aramco refinery and process piping applications. WC9 is the preferred specification where hydrogen partial pressure is elevated (hydrotreaters, hydrocrackers, hydrogen manifolds) — the higher Cr-Mo content places WC9 safely to the right of the Nelson Curve limits applicable to WC6. Gulf Union Ozone can confirm the correct alloy grade for your specific service conditions and SAEP-347 material number.

WC6 vs WC9 vs WCB — At a Glance
Property WCB WC6 WC9
AlloyC-Si1¼Cr-½Mo2¼Cr-1Mo
ASTM SpecA216A217A217
Max temp425 °C595 °C595 °C
H₂ serviceLimitedModeratePreferred
Typical useGeneral processCDU/VDU, steamHDT, HCK, H₂
Related Valve Pages
SAEP-347 Annex 4

Alloy Steel Valves in Saudi Aramco SAEP-347 Annex 4

Saudi Aramco Engineering Procedure SAEP-347 Annex 4 assigns 4-digit material numbers to approved valve configurations for direct use in material requisitions, purchase orders, and piping class specifications. WC6 and WC9 alloy steel valves appear as approved body materials in the Annex 4 matrix for gate valves and ball valves at multiple pressure classes.

Gulf Union Ozone's technical sales team works with SAEP-347 Annex 4 material numbers on a daily basis for EPC contractors, Saudi Aramco direct procurement agents, and approved vendor list (AVL) nominated suppliers. When you provide your SAEP-347 material number and quantity in your RFQ, we confirm stock availability, lead time for non-stock items, and the complete documentation package (EN 10204 3.1 MTC, API 598 hydrostatic test report, and CoC) within four business hours.

Alloy Steel Valve Types Stocked
  • ▸API 600 Gate Valves — WC6, WC9, rising stem, OS&Y, Class 150 to 2500
  • ▸API 6D Ball Valves — WC6, WC9, floating and trunnion, Class 150 to 1500
  • ▸Globe Valves — WC6, WC9, Class 150 to 1500, for throttling service
  • ▸Check Valves — WC6, WC9, swing and piston types, Class 150 to 1500
Documentation Package (Standard)
  • ▸EN 10204 Type 3.1 MTC — ASTM A217 chemistry + mechanicals
  • ▸API 598 hydrostatic test report (shell, seat, backseat)
  • ▸Certificate of Conformance (CoC)
  • ▸Heat treatment certificate (HT record — normalized and tempered)
  • ▸3.2 MTC (witnessed inspection) available on request
Need WC6 or WC9 alloy steel valves for a Saudi Aramco refinery project?

Provide your SAEP-347 material number, valve type, size, class, and quantity — and we confirm availability with EN 10204 3.1 MTCs within 4 business hours.

API 600 Gate Valves →

Selecting between ASTM A217 WC6 and WC9 for a Saudi Aramco alloy steel valve application depends on three process variables: service temperature, hydrogen partial pressure, and the applicable piping class in SAEP-347. WC6 (1¼Cr-½Mo) covers steam and hydrocarbon service continuously up to 595 °C and is specified in CDU, VDU, and high-temperature process piping classes. WC9 (2¼Cr-1Mo) applies wherever hydrogen partial pressure is elevated — hydrotreaters, hydrocrackers, and hydrogen distribution manifolds — because the higher chromium and molybdenum content provides resistance to hydrogen embrittlement and keeps the material safely to the right of the Nelson Curve limits that WC6 cannot safely meet at elevated temperature and hydrogen fugacity. The SAEP-347 Annex 4 material number for the valve specifies the required body material — cross-referencing with the project piping class confirms the correct alloy grade before placing the order.

FAQ

Frequently Asked Questions — Alloy Steel WC6 WC9 Valves

What is the difference between ASTM A217 WC6 and WC9 alloy steel valves?

Both WC6 and WC9 are chrome-molybdenum (Cr-Mo) alloy steel castings for high-temperature service, but differ in composition and application. WC6 is 1¼Cr-½Mo — maximum continuous 595 °C — the standard choice for steam, CDU/VDU, and process piping at elevated temperature. WC9 is 2¼Cr-1Mo — also 595 °C maximum but with higher creep strength and better resistance to hydrogen embrittlement, making it the preferred grade for hydrotreaters, hydrocrackers, and hydrogen manifold service. SAEP-347 Annex 4 includes both WC6 and WC9 variants; the correct grade depends on process fluid temperature and H₂ partial pressure per the applicable piping class.

When does Saudi Aramco specify alloy steel valves instead of carbon steel?

Saudi Aramco specifies alloy steel valves (WC6 or WC9) when service temperature exceeds the temperature rating of A216 WCB carbon steel — effectively above 425 °C continuous service. The specific triggers include: (1) steam and hydrocarbon service above 425 °C; (2) refinery units such as CDU, VDU, and atmospheric heater outlets; (3) hydrotreater and hydrocracker reactor feed/effluent service with elevated H₂ partial pressure; (4) any application where the Aramco piping class specifies Cr-Mo material. The SAEP-347 Annex 4 material number will indicate the required body material — WC6 or WC9 — for the specified valve type and pressure class.

What SAEP-347 material numbers cover WC6 and WC9 alloy steel valves?

SAEP-347 Annex 4 assigns separate 4-digit material numbers for each valve type, body material, and pressure class combination. WC6 and WC9 gate and ball valves have distinct Annex 4 material numbers at Class 150, 300, 600, 900, 1500, and 2500. The specific 4-digit number for your application depends on valve type, size, pressure class, and body material — confirm from the current SAEP-347 revision or contact Gulf Union Ozone's technical team. We work with SAEP-347 Annex 4 material numbers daily and can confirm the applicable number for your project's piping class and service conditions.

Are EN 10204 3.1 MTCs available for alloy steel WC6 WC9 valves from Saudi Arabia?

Yes. Gulf Union Ozone supplies EN 10204 Type 3.1 Mill Test Certificates (MTCs) for all alloy steel WC6 and WC9 valves. The 3.1 MTC confirms ASTM A217 chemical composition (Cr and Mo percentages), mechanical properties (tensile strength, yield strength, elongation), and heat treatment condition — normalized and tempered for WC6/WC9 castings. For Saudi Aramco projects under 04-SAMSS-002 and 04-SAMSS-035, the full documentation package includes the 3.1 MTC, API 598 hydrostatic test report, heat treatment certificate, and Certificate of Conformance. EN 10204 3.2 (with independent inspector witnessing at manufacturer) is available on request for critical service.

Saudi Aramco procurement documentation for alloy steel WC6 and WC9 valves requires a complete EN 10204 3.1 package: ASTM A217 chemical analysis confirming Cr and Mo percentages within grade limits, mechanical test results showing tensile strength, yield strength, and elongation, heat treatment records confirming normalized-and-tempered condition, and an API 598 hydrostatic test report for the assembled valve. Additional requirements under 04-SAMSS-002 (gate valves) or 04-SAMSS-035 (ball valves) include a Certificate of Conformance referencing the applicable Aramco Material System Specification and SAEP-347 Annex 4 material number. PMI (Positive Material Identification) per SAEP-1142 is mandatory for all alloy steel valves before final acceptance at Saudi Aramco Goods Receipt. Gulf Union Ozone supplies the complete documentation package with every alloy steel WC6 and WC9 valve order from our Jeddah warehouse.

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Quote Alloy Steel Valves — WC6, WC9, Ex-Stock Jeddah

Send your alloy steel valve requirement — valve type (gate, ball, globe, check), body material (WC6 or WC9), pressure class (ASME 150–2500), size (NPS), end connection, and SAEP-347 material number if available. We confirm stock availability, pricing, and EN 10204 3.1 MTC documentation within 4 business hours from our Jeddah warehouse.

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Gulf Union Ozone Trading Co. · CR 4030570569 · Jeddah, Saudi Arabia