Home Valve ComparisonsASME Class 900 vs Class 1500 Valves - High-Pressure Selection Guide

Valve Comparison Guide

ASME Class 900 vs Class 1500 Valves - High-Pressure Selection Guide

ASME Class 900 vs Class 1500 valves: compare pressure-temperature ratings, flange dimensions, weight, cost, and typical applications for high-pressure oil & gas, gas transmission, and HP steam service.

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Overview

ASME Class 900 Valve

ASME Class 900 (PN 150) valves are the first 'high-pressure' class in the ASME B16.5 series, bridging Class 600 utility service and Class 1500 very high-pressure service. Class 900 is common in gas gathering, HP steam, and offshore topside service.

ASME Class 900, DN25–DN600, WCB/SS 316L/Duplex 2205, API 6D or API 600, RFLG or RTJ flange faces

ASME Class 1500 Valve

ASME Class 1500 (PN 260) valves are used for very high-pressure gas injection, dense-phase CO₂, HP steam, and deep well applications. Class 1500 WCB is rated to 255.6 bar (3,707 psi) at 38°C - 67% higher than Class 900.

ASME Class 1500, DN25–DN300, WCB/A105/SS 316L, API 6D or API 600, RTJ flange face, pressure-seal bonnet

ASME Class 900 Valve or ASME Class 1500 Valve?

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Pros & Cons

ASME Class 900 Valve

Covers most offshore and onshore high-pressure gas gathering applications

Lighter and more compact than Class 1500 - lower weight on platform topsides

Lower cost than Class 1500 for the same size

WCB Class 900 rated to 153.4 bar (2,225 psi) at 38°C

Standard in NORSOK equipment with SS 316 or Duplex 2205 for North Sea

Not suitable for very high-pressure injection wells, HP gas compression, or HP steam above 153 bar

Pressure-seal bonnet typically required DN50+ in Class 900 - no bolted bonnet for this class in large sizes

Higher flanged dimensions than Class 600 - tighter pipe routing required

ASME Class 1500 Valve

Handles very high-pressure service - dense-phase CO₂, HP gas injection, HP turbine inlet steam

WCB Class 1500: 255.6 bar at 38°C; SS 316 Class 1500: 210 bar at 38°C

Required for HP HP compressor discharge and HP separator vessels (Class 1500 nozzles)

RTJ (Ring-Type Joint) flanges standard in Class 1500 for HP seal integrity

Forged bodies standard in smaller sizes (DN25–DN150) - superior to cast

Significantly heavier than Class 900 in same bore - major weight and space penalty on topsides

Higher cost - 40–80% more expensive than Class 900

Larger flange OD - difficult to specify in crowded piping

Pressure-seal bonnet required in all sizes - heavier bonnet assembly

ASME Class 900 Valve vs ASME Class 1500 Valve - Specification Comparison

Parameter	ASME Class 900 Valve	ASME Class 1500 Valve
Pressure Rating (WCB at 38°C)	153.4 bar (2,225 psi)	255.6 bar (3,707 psi)
Pressure Rating (SS 316 at 38°C)	128.3 bar (1,860 psi)	210 bar (3,045 psi)
ANSI / PN Designation	Class 900 / PN 150	Class 1500 / PN 260
Standard Flange Face	Raised Face (RF) or Ring-Type Joint (RTJ)	Ring-Type Joint (RTJ) - standard in most specs
Bonnet Design	Pressure-seal bonnet (Class 900 large bore)	Pressure-seal bonnet (all sizes typically)
Relative Weight	Base (1×)	1.5–2× Class 900 for same bore
Relative Cost	Base (1×)	1.4–1.8× Class 900 for same bore
Typical Application	Gas gathering 60–150 bar, HP steam 40–120 bar, offshore topsides	Gas injection 200–300 bar, CO₂ EOR, HP turbine inlet steam, deep well

When to Use Each

Use ASME Class 900 Valve when:

Gas gathering and transmission (60–150 bar operating pressure)

HP steam systems above 35 bar - IBR/ASME B31.1 service

Offshore platform production topsides

Subsea tree and manifold isolation at 5,000–10,000 psi wellhead pressure

Use ASME Class 1500 Valve when:

Gas injection compressor discharge - operating at 200–300 bar

Dense-phase CO₂ pipelines (EOR injection) - operating at 150–200 bar

HP steam systems - main steam above 150 bar in supercritical power plants

HP wellhead and Christmas tree isolation - Class 1500 ball or gate valves

Decision Guide

Specify Class 900 for offshore topsides, gas gathering pipelines, and HP steam systems operating below 150 bar. Specify Class 1500 for gas injection compressor discharge, dense-phase CO₂, HP supercritical steam, and any service where operating pressure exceeds 130 bar gauge. Never down-rate from Class 1500 to Class 900 without full engineering pressure-temperature calculation review - the consequences of valve failure at 200+ bar are catastrophic.

Frequently Asked Questions

Is Class 900 the same as PN 150 and Class 1500 the same as PN 260?

The ASME pressure classes (150, 300, 600, 900, 1500, 2500) are approximate PN designations: Class 900 ≈ PN 150, Class 1500 ≈ PN 260, Class 2500 ≈ PN 420. However, the exact pressure-temperature ratings differ depending on the material group per ASME B16.5 Table 2-1.1 through 2-3.9. Always use the actual P-T rating table for the specific material group (Group 1.1 for WCB, Group 2.1 for SS 316, etc.) - do not use PN approximations for engineering calculations.

Reviewed by Application Engineering, Vajra Industrial SolutionsDiscipline: Valve Application EngineeringLast reviewed: 20 June 2026