ASTM A105 WN & SO Flange Order

On April 8, 2025, we received an inquiry from a long-standing Singaporean client regarding ASTM A105 weld neck flanges and slip on flanges. As these products and materials are among our company’s top sellers, our sales representative promptly provided a quotation. The client accepted the price and proceeded to place an order.

Procurement List

ITEM	DESCRIPTION	Material	Product	Quantity	Unit
1	SLIP ON RF FLANGE ANSI CL.150# SERIES A	ASTM A105	SO RF Flange	4	EA
2	FLANGE WN RF(700MM),SERIES B, A105,ANSI-CL150#,ASME B16.47	ASTM A105	WN RF Flange	14	EA
3	FLANGE WN RF(1000MM),SERIES B, A105,ANSI-CL150#,ASME B16.47	ASTM A105	WN RF Flange	4	EA

What Is a Weld Neck Flange？

A weld neck (WN) flange is a high-integrity forged flange with a long tapered hub, designed to be butt-welded to the pipe.According to ASME B16.47, WN flanges in large diameters—such as 700 mm and 1000 mm—are commonly used in industrial pipelines, power plants, and offshore projects where structural reliability is crucial.

What Is a Slip On Flange？

A slip on (SO) flange is designed to slide over the pipe end and is then fillet-welded on both sides. Compared with WN flanges, SO flanges are easier to install and require less welding precision, making them ideal for low- to medium-pressure systems.Class 150 SeriesA SO flange is commonly used in water lines, HVAC systems, and general industrial pipelines where cost efficiency and simple assembly are essential.

ASTM A105 Material

ASTM A105 is a widely used carbon steel forging material for pressure-bearing flanges. It provides good strength, toughness, and weldability.

CHEMICAL	LIMITS	C	Mn	P	S	Si	Cu	Ni	Cr	Mo	V
ASTM A105	MIN		0.60			0.10
	MAX	0.35	1.05	0.035	0.040	0.35	0.40	0.40	0.30	0.12	0.08

ASME B16.47 Standard (Series A & B)

ASME B16.47 is the standard for large-diameter flanges (26″–60″), defining key requirements for dimensions, pressure ratings, and sealing surfaces. Series A offers a heavier design with more bolts for higher strength, while Series B has a lighter, more compact structure for easier installation. Both ensure reliable performance in demanding industrial pipelines.

Series A

– Heavier bolt loads
– Thicker flange sections
– Used in high-stress and critical industrial applications

Series B

– More economical bolt patterns
– Thinner sections
– Widely used in pipelines requiring standard sealing performance

Production, Packaging, and Transportation

Our flanges are produced under controlled forging and machining processes, with heat treatment as per ASTM A105 requirements. Each batch undergoes material certification and dimensional inspection against ASME B16.47. For packaging, flanges are individually protected (e.g., plastic caps, anti-rust coating) and securely crated in wooden cases to prevent damage during ocean freight. Clear marking with material grade, size, pressure rating, and heat number ensures traceability and easy identification upon delivery.