150# Stainless Steel Lap Joint Flange

ZIZI ENGEERING is a supplier of stainless steel forged flange for overseas customers. With advanced production equipment and high-quality services, we have won the trust of many customers around the world. On February 7, 2025, we received an order for stainless steel lap joint flange from a new customer from China. We quickly quoted the customer and received the order on February 10.

The main structural feature of the stainless steel lap joint flange is the loose connection. It consists of a flange body, a flange nipple and connecting bolts. The flange body and the flange nipple are loose fitting, and this structure allows the pipeline to expand and contract freely within a certain range.

Inspection photos

 

Stainless Steel Lap Joint Flange – Overview

A Lap Joint Flange is a two-piece flange system that consists of:

1. A loose backing flange
2. A stub end (or lap joint stub end)

This design allows the flange to rotate freely, making it easier to align bolt holes and adjust connections. Lap joint flanges are commonly used in low-pressure, non-critical applications, especially where frequent dismantling is required.

Key Features of Stainless Steel Lap Joint Flanges

Flexible & Adjustable – The flange can rotate, simplifying bolt alignment
Corrosion Resistance – Stainless steel resists rust and oxidation
Easy Installation & Removal – Ideal for systems requiring frequent maintenance
Cost-Effective – The backing flange can be made of a less expensive material
Compatible with Stub Ends – Requires a matching stub end to function

Specification of ASME B16.5 Lap Joint Flange

Size Range	1/2″ – 24” / DN15 – DN600
Pressure Rating	Class 150, 300, 600, 900, 1500, 2500lb
Standard	ASME B16.5, EN1092-1
Stainless Steel	ASTM A182 F304/304L/304H, 316/316L, 310S, 317,347,904L

SS304/304L Stainless Steel 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 F304L	MIN						8.00	18.00
	MAX	0.03	2.00	0.045	0.030	1.00	13.00	20.00		0.10

SS304/304L Stainless Steel Flange

MATERIAL	ASTM A182 F304	ASTM A182 F304L
T.S (MPA)	515 min	485 min
Y.S (MPA)	205 min	170 min
EL %	30 min	30 min
R/A %	50 min	50 min

Class 150 lb LAPJ Flange Dimensions

NPS	A	B	C	D	R	F	H	I	J	W
	inch						No. of Holes	inch		kg/pc
	mm							mm
1/2	3.500	0.900	0.440	0.620	0.120	1.190	4	0.620	2.380	0.38
	88.90	22.90	11.20	15.70	3.000	30.20		15.70	60.45
3/4	3.880	1.110	0.500	0.620	0.120	1.500	4	0.620	2.750	0.55
	98.60	28.20	12.70	15.70	3.000	38.10		15.70	69.85
1	4.250	1.380	0.560	0.690	0.120	1.940	4	0.620	3.120	0.76
	108.0	35.10	14.20	17.50	3.000	49.30		15.70	79.25
1-1/4	4.620	1.720	0.620	0.810	0.190	2.310	4	0.620	3.500	1.01
	117.3	43.70	15.70	20.60	4.800	58.70		15.70	88.90
1-1/2	5.000	1.970	0.690	0.880	0.250	2.560	4	0.620	3.880	1.30
	127.0	50.00	17.50	22.40	6.400	65.00		15.70	98.60
2	6.000	2.460	0.750	1.000	0.310	3.060	4	0.750	4.750	2.03
	152.4	62.5	19.10	25.40	7.900	77.70		19.10	120.7
2-1/2	7.000	2.970	0.880	1.120	0.310	3.560	4	0.750	5.500	3.25
	177.8	75.40	22.40	28.40	7.900	90.40		19.10	139.7
3	7.500	3.600	0.940	1.190	0.380	4.250	4	0.750	6.000	3.81
	190.5	91.40	23.90	30.20	9.700	108.0		19.10	152.4
3-1/2	8.500	4.100	0.940	1.250	0.380	4.810	8	0.750	7.000	4.76
	215.9	104.1	23.90	31.75	9.700	122.2		19.10	177.8
4	9.000	4.600	0.940	1.310	0.440	5.310	8	0.750	7.500	5.25
	228.6	116.8	23.90	33.30	11.20	134.9		19.10	190.5
5	10.00	5.690	0.940	1.440	0.440	6.440	8	0.880	8.500	6.02
	254.0	114.5	23.90	36.60	11.20	163.6		22.40	215.9
6	11.00	6.750	1.000	1.560	0.500	7.560	8	0.880	9500	7.40
	279.4	171.5	25.40	39.60	12.70	192.0		22.40	241.3
8	13.50	8.750	1.120	1.750	0.500	9.690	8	0.880	11.75	12.1
	342.9	222.3	28.40	44.50	12.70	246.1		22.40	298.5
10	16.00	10.92	1.190	1.940	0.500	12.00	12	1.000	14.25	16.4
	406.4	277.4	30.20	49.30	12.70	304.8		25.40	362.0

Applications of Stainless Steel Lap Joint Flanges

Piping Systems Requiring Frequent Dismantling
Marine & Offshore Industry – Corrosion-resistant seawater piping
Food & Beverage Industry – Hygienic processing lines
Pharmaceutical & Chemical Processing – Acidic and corrosive environments
Water Treatment Plants – Wastewater and filtration systems