Stainless Steel Lap Joint Flange

In the complex network of industrial piping system, flange as a key hub connecting piping and equipment, its performance and applicability directly affect the operational efficiency and safety of the entire system.Stainless steel lap joint flange strictly follows the authoritative standards set by the American Society of Mechanical Engineers (ASME), and have become the ideal choice for piping connection in many industries due to their unique structural design and excellent comprehensive performance. Whether for corrosive media transportation or frequent disassembly and assembly, stainless steel lap joint flanges can provide stable protection for industrial piping systems with scientific design and reliable performance.

What Is a Lap Joint Flange?

Lap joint flanges typically consist of two parts: a stub end and a lap joint flange ring. The design of this flange construction allows the flange ring to be separated from the Stub End, providing flexibility in installation and removal, especially for pipe connections that require frequent disassembly or lined piping systems. Loose flanges are commonly used in the petroleum, chemical, and pharmaceutical industries for their ability to reduce material costs and simplify maintenance, as well as for their good corrosion resistance and adaptability.

Specification of 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
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 / 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

Stainless Steel LAPJ Flange Material Analysis:

Chemical Composition:

Flange as a core connector, the chemical composition of its material plays a decisive role in the performance, stainless steel loose set flange with strict chemical composition control as the cornerstone, through the carbon, manganese, phosphorus, sulfur and other elements of the scientific proportioning, endowed with excellent strength, toughness and corrosion resistance of the product.

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo	N	Ti	Cu
ASTM A182 F304	MIN						8	18
	MAX	0.08	2	0.045	0.03	1	11	20		0.1
ASTM A182 F304H	MIN	0.04					8	18
	MAX	0.1	2	0.045	0.03	1	11	20
ASTM A182 F304L	MIN						8	18
	MAX	0.03	2	0.045	0.03	1	13	20		0.1
ASTM A182 F316	MIN						10	16	2
	MAX	0.08	2	0.045	0.03	1	14	18	3	0.1
ASTM A182 F316L	MIN						10	16	2
	MAX	0.03	2	0.045	0.03	1	15	18	3	0.1
ASTM A182 F317	MIN						11	18	3
	MAX	0.08	2	0.05	0.03	1	15	20	4
ASTM A182 F321	MIN						9	17		0.1	5(C+N)
	MAX	0.08	2	0.05	0.03	1	12	19			0.7
ASTM A182 F321H	MIN	0.04					9	17			4(C+N)
	MAX	0.1	2	0.045	0.03	1	12	19			0.7
ASTM A182 F347	MIN						9	17
	MAX	0.08	2	0.045	0.03	1	13	20
ASTM A182 F904L  (N08904)	MIN						23	19	4			1
	MAX	0.02	2	0.04	0.03	1	28	23	5	0.1		2

Mechanical Properties:

Mechanical properties are the characteristics of the material’s response to the action of external forces, reflecting the ability of the material to resist deformation and fracture. Key mechanical property parameters include yield strength, tensile strength, elongation and so on.

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %	R/A %
ASTM A182 F304	515 min	205 min	30 min	50 min
ASTM A182 F304H	515 min	205 min	30 min	50 min
ASTM A182 F304L	485 min	170 min	30 min	50 min
ASTM A182 F316	515 min	205 min	30 min	50 min
ASTM A182 F316L	485 min	170 min	30 min	50 min
ASTM A182 F317	515 min	205 min	30 min	50 min
ASTM A182 F321	515 min	205 min	30 min	50 min
ASTM A182 F321H	515 min	205 min	30 min	50 min
ASTM A182 F347	515 min	205 min	30 min	50 min
ASTM A182 F904L	490 min	215 min	35 min

Dimension of Lap Joint Flange:

ZIZI specializes in the production and supply of various types of lap joint flanges, which cover pressure values including 150#, 300#, 600#, 900#, 1500#, 2500#.

150# lap joint flange:

 

Nominal Pipe Size		A	B	C	D	R	F	H	I	J	Weight
inch	mm	mm	mm	mm	mm	mm	mm	Holes	mm	mm	kg / piece
1/2	21.30	88.90	22.90	11.20	15.70	3.000	30.20	4	15.70	60.45	0.38
3/4	26.70	98.60	28.2	12.70	15.70	3.000	38.10	4	15.70	69.85	0.55
1	33.40	108.0	35. 10	14.20	17.50	3.000	49.30	4	15.70	79.25	0.76
11/4	42.20	117.3	43.70	15.70	20.60	4.800	58.70	4	15.70	88.90	1.01
11/2	48.30	127.0	50.00	17.50	22.40	6.400	65.00	4	15.70	98.60	1.30
2	60.30	152.4	62.50	19. 10	25.40	7.900	77.70	4	19.10	120.7	2.03
21/2	73.00	177.8	75.40	22.40	28.40	7.900	90.40	4	19.10	139.7	3.25
3	88.90	190.5	91.40	23.90	30.20	9.700	108.0	4	19.10	152.4	3.81
31/2	101.6	215.9	104.1	23.90	31.75	9.700	122.2	8	19.10	177.8	4.76
4	114.3	228.6	116.8	23.90	33.30	11.20	134.9	8	19.10	190.5	5.25
5	141.3	254.0	114.5	23.90	36.60	11.20	163.6	8	22.40	215.9	6.02
6	168.3	279.4	171.5	25.40	39.6	12.70	192.0	8	22.40	241.3	7.40
8	219. 1	342.9	222.3	28.40	44.50	12.70	246. 1	8	22.40	298.5	12.1
10	273.0	406.4	277.4	30.20	49.30	12.70	304.8	12	25.40	362.0	16.4
12	323.8	482.6	328.2	31.75	55.60	12.70	365.3	12	25.40	431.8	26.1
14	355.6	533.4	360.2	35. 10	79.25	12.70	400. 1	12	28.40	476.3	34.5
16	406.4	596.9	411.2	36.60	87.40	12.70	457.2	16	28.4	539.8	44.6
18	457.2	635.0	462.3	39.60	96.80	12.70	505.0	16	31.75	577.9	48.7
20	508.0	698.5	514.4	42.90	103.1	12.70	558.8	20	31.75	635.0	61.6
24	609.6	812.8	616.0	47.80	111.3	12.70	663.4	20	35.10	749.3	86.6

Advantages of Stainless Steel Lap Joint Flange:

Excellent corrosion resistance: stainless steel is extremely resistant to corrosive media such as acid, alkali, salt, etc. It is suitable for petrochemical, pharmaceutical, food and other industries.

Convenient installation and low maintenance cost: only need to dismantle the flange ring when overhauling, no need to cut the pipeline or destroy the welded joints, which significantly reduces the maintenance cost.

Economy and flexibility: the same flange ring can be matched with short joints made of different materials, which can flexibly cope with pipeline upgrading or medium change demands.

Long life and reliability: Stainless steel is not easy to crack under cyclic load, extending the service life of the flange system.

Areas of Application：

Petrochemical industry: corrosive media transportation, frequent maintenance pipeline

Food and pharmaceutical industry: sanitary piping, CIP cleaning system

Marine and ship engineering: seawater piping, ship hydraulic system

Energy and power: thermal piping, nuclear power auxiliary system

Water treatment and environmental protection: sewage treatment, desulfurization and denitrification systems

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.

Frequently Asked Questions (FAQs)

What is the difference between a lap joint flange and a flange?

Lap joint flange is a kind of special structure flange, which is composed of stub end and lap joint flange ring. When connecting with the pipeline, the flange body is not directly welded with the pipe, but is connected through the flanging short section to realize the connection. This structure makes the Lap joint flange can be freely adjusted bolt hole position during installation, with good alignment and convenient disassembly performance, especially suitable for frequent disassembly or alignment difficulties in the pipeline system. In contrast, “flange” is a broad concept, covering a wide range of types including butt weld flanges, slip on flanges, blind flanges, etc., with different structures and connection methods, which are suitable for different working conditions and pressure levels.

8 7 月, 2025