A240 304H P Number Welding Group and Classification

A240 304H P Number: Welding Group and Classification

At Gangsteel, a leading manufacturer and exporter of stainless steel products, we supply high-quality A240 304H stainless steel plates compliant with ASTM A240 and ASME SA 240 standards. A240 304H, also known as AISI 304H, UNS S30409, or EN 1.4948, is a high-carbon austenitic stainless steel optimized for high-temperature strength and creep resistance up to 1500°F (815°C). This guide explains the P Number, welding group, and classification for A240 304H under ASME Section IX, along with its properties and applications for uses like plat stainless 304 and SA 240 GR 304 pipe. For inquiries, contact us at admin@gangsteel.com or explore our ASME SA240 Stainless sheet offerings.

P Number for A240 304H Stainless Steel

The P Number for A240 304H is P8, Group 1, as classified under ASME Section IX for welding procedure qualifications. P Numbers group base metals with similar weldability, mechanical properties, and base metal grouping for procedure qualification. Austenitic stainless steels like 304H are assigned P8 due to their high chromium and nickel content, ensuring compatibility in welding processes.

 Group 1 within P8 includes non-stabilized austenitic grades with carbon ≤0.10%, encompassing 304H's high-carbon composition (0.04-0.10%). This classification simplifies welding qualification, allowing procedures for P8 Group 1 to apply broadly to 300-series austenitics. For low-carbon variants, see sa240 gr 304l.

Welding Group and Classification

• Welding Group: P8 Group 1 – Includes austenitic stainless steels with carbon ≤0.10%, such as 304, 304H, and 316. Group 1 is for non-stabilized grades, distinguishing it from Group 2 (stabilized with Ti or Nb, like 321 or 347).
• Classification: Base metal group for procedure qualification per ASME IX, QW/QB-422. It requires impact testing for low temperatures but no for high-temperature service. Filler metals are typically F8 (austenitic fillers like ER308H).
• Importance: Ensures welds match base metal strength (tensile 515 MPa min) and corrosion resistance, critical for high-temperature applications like boilers.

See sa240 gr 304h for stock.

Chemical Composition

Carbon (0.04-0.10%) aids creep resistance. See sa240 gr 304l.

Mechanical Properties

High-temperature: Allowable stress 25.5 ksi at 1000°F (538°C).

Physical Properties

• Density: 8.00 g/cm³.
• Melting Point: 1400-1450°C.
• Thermal Conductivity: 16.2 W/m·K.
• Coefficient of Thermal Expansion: 17.2 × 10⁻⁶/K.
• Max Service Temperature: 1500°F (815°C) continuous.

Corrosion Resistance

A240 304H resists mild acids and atmospheric conditions, outperforming SS204 vs SS 304. Higher carbon risks sensitization in welds; anneal for protection. See sa240 gr 316l for chlorides.

Weldability

Fair with ER308H fillers; low heat input (<2.0 kJ/mm) and annealing required. See sa240 gr 321.

Applications

A240 304H is used in:

• Boilers and pressure vessels.
• Heat exchangers.
• Power generation piping.
• High-temperature chemical processing.

For cost-effective options, see sa240 gr 201.

Pricing and Availability

As of October 19, 2025, A240 304H plate prices (2B finish, 3-6mm) range from $1.60-$3.50/kg. Gangsteel offers $1.60/kg FOB (MOQ 1 ton) for sa240 gr 304h. Contact admin@gangsteel.com or visit astm a 240 stainless plate.

FAQ on A240 304H P Number

What is the P Number for A240 304H stainless steel?

P8, Group 1, under ASME Section IX, for austenitic stainless steels with carbon ≤0.10%.

What is the welding group for A240 304H?

P8 Group 1, including non-stabilized austenitics like 304H, for procedure qualification.

What is the classification of A240 304H in ASME Section IX?

Base metal group QW/QB-422 for austenitic stainless steels, requiring impact testing for low temperatures but not for high-temperature service.

How does the P Number affect welding A240 304H?

P8 Group 1 simplifies qualification; use F8 fillers like ER308H for matching strength and corrosion resistance.

Why is P8 Group 1 important for A240 304H?

It groups 304H with similar weldable austenitics, ensuring compatibility for high-temperature welds in boilers.