Stainless Steel Weld Neck Flange

On 23^rd January, we received an inquiry from Colombia. It is about weld neck flange in stainless steel 316 with some requirements on product marking and MTR.

In recent years, we’ve exported plenty of flanges in all types for our clients worldwide. Thus we can perfectly fulfill demands of this Colombia clients.

Then, After discussing detailed demands for the goods, the client placed order 6 days later. The flanges are delivered by DHL to Colombia after 10 days.

At last, Before delivering, we showed photos of the marking and package for our client and put the physical certificate in the wooden case as required.

 

Specification of Forged Weld Neck Flange

 

A Stainless Steel Weld Neck Flange is a type of pipe flange that is used to connect pipes, valves, and other equipment in piping systems. The distinguishing feature of a weld neck flange is its long tapered neck, which is welded directly to the pipe, providing a strong, durable, and leak-resistant connection. The design helps to reduce stress at the point of connection, making it ideal for high-pressure and high-temperature applications.

Shape Type	Regular and Long Neck
Sealing Face	RF, FF, FTJ
Size Range	1/2″ – 48″/ DN15 – DN1200
Pressure Rating	Class 150, 300, 600, 900, 1500, 2500lb
Standard	ASME B16.5, ASME B16.47 Series A/B
Stainless Steel	ASTM A182 F304/304L/304H, 316/316L, 310S, 317,347,904L

Stainless Steel Forged Flange Chemical Composition

 

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo	N
ASTM A182 F304	MIN						8.0	18.0
	MAX	0.08	2.00	0.045	0.030	1.00	11.0	20.0		0.10
ASTM A182 F316	MIN						10.0	16.0	2.00
	MAX	0.08	2.00	0.045	0.030	1.00	14.0	18.0	3.00	0.01

Stainless Steel Forged Flange Mechanical Property

 

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo	N
ASTM A182 F304	MIN						8.0	18.0
	MAX	0.08	2.00	0.045	0.030	1.00	11.0	20.0		0.10
ASTM A182 F316	MIN						10.0	16.0	2.00
	MAX	0.08	2.00	0.045	0.030	1.00	14.0	18.0	3.00	0.01

Class 150 lb Weld Neck Flange Dimensions  

 

NPS	A	B	C	D	E	F	G	H	I	J	W
	inch							No. of Holes	inch		kg/pc
	mm								mm
1/2	3.500	0.620	0.440	1.880	0.840	1.190	1.380	4	0.620	2.380	0.48
	88.90	15.70	11.20	47.80	21.30	30.20	35.00		15.70	60.45
3/4	3.880	0.820	0.500	2.060	1.050	1.500	1.690	4	0.620	2.750	0.71
	98.60	20.80	12.70	52.30	26.70	38.10	42.90		15.70	69.85
1	4.250	1.050	0.560	2.190	1.320	1.940	2.000	4	0.620	3.120	1.01
	108.0	26.70	14.20	55.60	33.50	49.30	50.80		15.70	79.25
1-1/4	4.620	1.380	0.620	2.250	1.660	2.310	2.550	4	0.620	3.500	1.33
	117.3	35.10	15.70	57.15	42.20	58.70	63.50		15.70	88.90
1-1/2	5.000	1.610	0.690	2.440	1.900	2.560	2.880	4	0.620	3.880	1.72
	127.0	40.90	17.50	62.00	48.30	65.00	73.15		15.70	98.60
2	6.000	2.070	0.750	2.500	2.380	3.060	3.620	4	0.750	4.750	2.58
	152.4	52.60	19.10	63.50	60.45	77.70	91.90		19.10	120.7
2-1/2	7.000	2.470	0.880	2.750	2.880	3.560	4.120	4	0.750	5.500	4.11
	177.8	62.70	22.40	69.85	73.15	90.40	104.6		19.10	139.7
3	7.500	3.070	0.940	2.750	3.500	4.250	5.000	4	0.750	6.000	4.92
	190.5	78.00	23.90	69.85	88.90	108.0	127.0		19.10	152.4
3-1/2	8.500	3.550	0.940	2.810	4.000	4.810	5.500	8	0.750	7.000	6.08
	215.9	90.20	23.90	71.40	101.6	122.2	139.7		19.10	177.8
4	9.000	4.030	0.940	3.000	4.500	5.310	6.190	8	0.750	7.500	6.84
	228.6	102.4	23.90	76.20	114.3	134.9	157.2		19.10	190.5
5	10.00	5.050	0.940	3.500	5.560	6.440	7.310	8	0.880	8.500	8.56
	254.0	128.3	23.90	88.90	141.2	163.6	185.7		22.40	215.9
6	11.00	6.070	1.000	3.500	6.630	7.560	8.500	8	0.880	9.500	10.6
	279.4	154.2	25.4	88.90	168.4	192.0	215.9		22.40	241.3
8	13.50	7.980	1.120	4.000	8.630	9.690	10.62	8	0.880	11.75	17.6
	342.9	202.7	28.40	101.6	219.2	246.1	269.7		22.40	298.5

How to inspect weld neck flange?

 

Visual Inspection

✅ Check for Surface Defects

Look for cracks, pitting, corrosion, and rough machining on the flange face, neck, and bore.

Ensure there are no burn marks, rust, or discoloration from improper welding or heat treatment.

Further, Examine for dents, scratches, or gouges that could affect sealing performance.

 

Dimensional Inspection

✅ Verify Dimensions as per ASME B16.5 / B16.47

Outer & Inner Diameter (OD & ID) – Check flange size matches the piping system.

Bolt Hole Diameter & Pitch Circle Diameter (PCD) – Ensure holes are evenly spaced for proper bolting.

Neck Thickness & Hub Length – Measure to ensure proper stress distribution.

Facing Finish – Raised Face (125-250 AARH), RTJ groove dimensions.

Applications of Stainless Steel WN Flanges

 

High-pressure systems like power plants, oil and gas piping, and chemical plants.

Heat exchangers and boilers, where strength and tightness of the connection are critical.

Refineries, offshore platforms, and nuclear facilities.

Marine environments, where corrosion resistance is a must.

Cryogenic applications where extreme low temperatures are involved.

 

Benefits of Stainless Steel WN Flanges

 

•  High strength and stress distribution – ideal for high-pressure, high-temperature environments.
•  Leak-resistant – full penetration weld ensures a permanent seal.
• Corrosion resistance – perfect for marine, chemical, and food processing applications.
•  Low maintenance and long-term durability – fewer repairs needed.
•  Widely applicable – versatile for many industries and pressures.
•  Safety and reliability – reduced risk of flange failure.