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Lap Joint Flanges

Lap Joint Flanges

Similar to Slip-on flange, a socket-weld flange however has a recession machined into the hub side of the flange with width equal to the thickness of the pipe. Usually developed for small sizes, these socket-weld flanges are beneficial for pressure applications. Socket Weld Flange is welded to a pipe with one fillet weld over the socket with no primary alignment practice required.

The passive Strength of the socket-weld flange is 2/3rd that of weld neck and fatigue strength is equal to slip-on flange.
While welding the pipe to the socket-weld flange one must mind a clearance gap between the pipe and the seat of the recession in order to reduce the residual stress at the root of the weld. The space between the pipe and the seat however allows settlement of the fluid and induces erosion and corrosion at the gap which is a major disadvantage of using a socket-weld flange.

Lap Joint Flanges(Loose Flanges) are used with a corresponding stub-end that "inserts" in the inside of the flange. The main benefit of this type of flange, is that once the pipe welds to the insert stub-end, the flange then can rotate for easier alignment of the bolting holes. However, lap joint flanges and their stub-ends' ability to hold pressure is about the same as slip-on flanges. They are not suitable for situations with a high external or changing loads of force. They do provide an advantage in a piping system that needs frequent dismantling for inspection or to remove build-up


Lap Joint Plate Flange can be manufactured as forged or directly machined from plates. Whereas Stub has to be manufactured as wrought from parent Pipe, seamless or welded by cold press or hot press method.


lap Joint Flanges are preferred for low cost pipeline projects specially civil water pipeline projects, Chemical Processing, Paint & Food Processing units & some sector of Oil & Gas pipelines.

Common Material Specifications for Lap Joint Flange As per international Standard
ASTM A105 Carbon Steel Flanges
ASTM A181 Carbon Steel Flanges
ASTM A182 Stainless Steel & Chrome Moly Alloy Steel Flanges
ASTM A350 Carbon Steel & Chrome Moly Alloy Steel Flanges
ASTM A694 Carbon Steel Flanges
ASTM A707 Carbon Steel Flanges
ASTM A727 Carbon Steel Flanges
ASTM B124 Copper & Copper Alloy Flanges
ASTM B247 Aluminum & Aluminum Alloy Flanges
ASTM B381 Titanium Alloy Flanges
ASTM B462 Nickel Alloy Flanges
ASTM B493 Zirconium & Zirconium Alloy Flanges
ASTM B564 Nickel & Nickel Alloy Flange

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Stainless steel Flanges ( product range)
WN – Welding Neck EN-TYPE 11
BL – Blind EN-TYPE 05
SO – Slip On EN-TYPE 01/12
LJ – Lap Joint EN-TYPE 02/04
SW – Socket Weld EN-TYPE 14
THR – Threaded EN-TYPE 13
LWN – Long Welding Neck / Integral EN-TYPE 21
Welding Collars EN-TYPE 32/34
ORIFICE Flanges, Swivel Flanges, Spades, Spacer Rings
Spectable Blinds, API 6A, JIS B2220, VSM, NFE, BS10/BS4504, GOST

F304/304L 1.4301/1.4307 UNS S30403/S30400
F304H 1.4948 UNS S30409
F321/F321H 1.4541/1.4878 UNS S32100/S32109
F316/F316L 1.4401/1.4404 UNS S31603/S31600
F316L (MO+) 1.4435 UNS S31635
F316TI 1.4571 UNS S31635
F904L 1.4539 UNS N08904
F44 (254SMO®) 1.4547 UNS S31254
F310/F310S 1.4841/1.4845 UNS S31000/S31008
F347 (H) 1.4550 UNS S34700/S34709
F317L 1.4438 UNS S31703
F316H 1.4919 UNS S31609

Duplex & Super Duplex:
F51/F60 1.4462 UNS S31803
F53 1.4410 UNS S32750
F55 1.4501 UNS S32750

Nickel Alloys:
Alloy 800/800H 1.4876 UNS N08800/N08810
Monel 400 2.4360 UNS N04400
Alloy 600 2.4816 UNS N06600
Alloy 625 2.4856 UNS N06625
Alloy 825 2.4858 UNS N08825
Alloy C276 2.4819 UNS N10276
Alloy 59 2.4605 UNS N06059
Alloy C4 2.4610 UNS N06455
Alloy 22 2.4602 UNS N06022
Other Alloys available on request

Sizes according to ASME/ASTM B16.5 – B16.36 – B16.48
Class 150(lb) up to 24″
Class 300(lb) up to 20″
Class 600(lb) up to 20″
Class 900(lb) up to 16″
Class 1500(lb) up to 10″
Class 2500(lb) up to 8″

Sizes according to DIN – EN1092-1 – EN1759-1 – NFE – BS10/BS4504 & ISO7005-1
PN2.5/PN06/PN10 up to DN800
PN16/PN25/PN40 up to DN600
PN63/PN100 up to DN500
PN160/PN250 up to DN300
PN320/PN400 up to DN200
API 6A Flanges
2000 PSI up to 20000 PSI
JIS B2220
5K up to 63K

ASTM/ASME B16.5/B16.48/B16.36
EN 10222-1/EN10222- 5
EN 1092-1/EN 1759-1
BS 10/BS 4504 (British Standard)
JIS B2220 – NFE – GOST – VSM – API 6A
ISO 7005-1 – NORSOK L005

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  • Nanubhai Desai Road,
  • Mumbai-400004.
  • Tel : +91-22-23868818/23854314
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Industries We Serve

  • Oil & Gas
  • Petrochemicals
  • Agro chemicals
  • Fire Safety Product
  • Shipping
  • Engineering
  • Dairy & Food Processing
  • pharmaceutical
  • Automobiles

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