ASTM A350 Socket Weld Flange

In critical industrial fields such as petrochemical, cryogenic engineering and electric power, the reliability and safety of piping systems are of paramount importance. ASTM A350 socket weld flange, as the core component of piping connection, whose material performance directly determines the operational stability of the whole system, are widely used in industrial fields such as petroleum, natural gas and chemical industries.

What Is an ASTM A350 Socket Weld Flange?

ASTM A350 is a technical specification developed by the American Society for Testing and Materials (ASTM) specifically for carbon and low alloy steel forgings for use in low temperature environments.

Socket weld flanges, as one of the important products covered by this standard, are a type of flange connection in which the end of the pipe is inserted into the flange ring step and welded at the end and outside of the pipe.

The main material grades of socket weld flanges under ASTM A350 include several grades such as LF1, LF2, LF3, LF5, LF6, andLF9, etc. These material grades ensure that excellent mechanical properties and notch toughness can still be maintained at low temperatures through strict control of chemical compositions and heat treatment processes.

Specification of Socket Weld Flange:

Size Range	1/2″- 3″ / DN15 – DN80
Pressure Rating	Class 150, 300, 600, 1500
Standard	ANSI / ASME B16.5
Carbon Steel	ASTM A105 / A105N
Low Temp Carbon Steel	ASTM A350 LF2 / LF3
Pipeline Steel	ASTM A694 F42 / 46 / 56 / 60 / 65
Alloy Steel	ASTM A182 F11 / 12 / 12 / 5 / 9 / 91 / 92
Stainless Steel	ASTM A182 F304 / 304L / 304H, 316 / 316L, 310S, 317, 347, 904L
Duplex Stainless Steel	ASTM A182 F51, F53, F44

ASTM A350 SW Flange Material Analysis:

chemical composition：

The chemical composition of ASTM A350 is critical to its performance, and proper elemental ratios ensure not only good strength, toughness, and compression resistance, but also stability and safety in high-temperature and high-pressure environments.The commonly used LF1 and LF2 are analyzed below.

CHEMICAL	LIMITS	C	Mn	P	S	Si	Cu	Ni	Cr	Mo	V	Nb
ASTM A350 LF2	MIN		0.60			0.15
ASTM A350 LF2	MAX	0.30	1.35	0.035	0.040	0.35	0.40	0.40	0.30	0.12	0.08	0.02
ASTM A350 LF3	MIN					0.20		3.30
ASTM A350 LF3	MAX	0.20	0.90	0.04	0.04	0.35	0.40	3.70	0.30		0.03

Mechanical Properties：

Mechanical properties is a measure of stainless steel pipe can play a stable role in the core indicators, related to industrial equipment safety and engineering life.The commonly used LF1 and LF2 are analyzed below.

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %	R/A %	HARDNESS
ASTM A350 LF2	485-655	250 min	22 min	30 min	197 max
ASTM A350 LF3	485-655	260min	22min	35min

Dimension of Socket Weld Flange:

ZIZI specializes in the production and supply of various types of socket weld flanges, which cover pressure values including 150#, 300#, 600#, 1500# .

600# threaded flange:

Nominal Pipe Size		A	B	C	D	E	K	F	G	H	I	J	Weight
inch	mm	mm	mm	mm	mm	mm	mm	mm	mm	Holes	mm	mm	kg / piece
1/2	21.30	95.20	To be specified by the Purchaser	14.20	22.30	22.40	9.60	38.10	35.10	4	15.70	66.55	0.76
3/4	26.70	117.3		15.70	25.40	27.70	11.10	47.70	42.90	4	19.10	82.50	1.29
1	33.40	123.9		17.50	26.90	34.50	12.70	53.80	50.80	4	19.10	88.90	1.55
11/4	42.20	133.3		20.60	28.40	43.20	14.20	63.50	63.50	4	19.10	98.60	2.06
11/2	48.30	155.4		22.30	31.75	49.50	15.70	69.85	73.15	4	22.30	114.3	3.00
2	60.30	165.1		25.40	36.60	62.00	17.50	84.00	91.90	8	19.10	127.0	3.67
21/2	73.00	190.5		28.40	41. 10	74.70	19.00	100.0	104.6	8	22.30	149.3	5.35
3	88.90	209.5		31.75	46.00	90.70	20.60	117.3	127.0	8	22.30	168.1	7.06

Advantages of Socket Weld Flanges：

Reliable welding structure and high strength: the socket flange adopts fillet welding connection, and the pipe is inserted into the flange socket for one round of external welding to form a stable and firm structure.

Superior sealing performance: the pipe is inserted into the internal flange to form a natural centering structure, the inner wall is flat after welding, and there is no weld protrusion, so it can form a uniform pressure distribution on the sealing surface after the sealing gasket is pressed to prevent the medium from leaking.

Suitable for small-diameter high-pressure systems: socket flanges have a compact structure and small installation space, especially suitable for small-diameter piping systems from one-half inch to three inches.

Easy installation and high welding efficiency: socket flanges do not require beveling and alignment for installation, easy operation and reduced welding process.

Smooth inner wall, reduce flow resistance: welded joints are located on the outside of the pipeline, the inside of the pipeline remains smooth, there will be no weld bulge or weld slag accumulation, which is conducive to improving the medium flow rate and reducing the resistance of the system.

Multi-standard adaptation, easy to international common: socket flanges can be manufactured according to a variety of international standards to meet the needs of different working conditions, especially suitable for export or international engineering projects.

Inspection:

Outer diameter: Ensure that the overall flange size meets the installation space and piping design requirements.

Inner Diameter: Ensure that the flange matches the pipeline threads to avoid over-loosening, over-tightening or connection failure.

Thickness: Ensure that the flange has pressure-bearing capacity to avoid deformation or rupture due to insufficient strength.

Number and position of bolt holes: to ensure the consistency of assembly and uniform force, to avoid assembly offset and poor connection.

Areas of Application：

Oil and gas extraction: wellhead units, extraction trees and gathering pipelines.

Petroleum refining and transportation: in the oil and gas pipeline, refinery distillation tower and reactor import and export pipeline.

Chemical production: for reactor connection piping, highly toxic media and strong corrosive liquid transportation piping.

Pharmaceutical and food processing: for injection production lines, aseptic material transportation pipelines and online cleaning systems.

Thermal power generation and heating: main steam piping, high temperature and high pressure hydrophobic piping and waste heat boiler connection piping.

Nuclear power and hydrogen energy: auxiliary piping for nuclear power plants, hydrogen fuel cell hydrogen supply piping.

Shipbuilding: nacelle fuel oil piping, ballast water system and deck steam tracing piping.

ZIZI specializes in the production of various flanges of different types and materials, and the products are widely used in many industries, such as petroleum, chemical, electric power, shipbuilding, pharmaceutical, food, construction and so on. The company has advanced production equipment and perfect testing means, including multiple cold drawing machines, cold rolling machines, automatic welding equipment, hydraulic testing machines, spectral analyzers, non-destructive testing equipment, etc., to ensure that each flange meets the relevant standards at home and abroad.