Lap Joint Flanges – ASME/ANSI B16.5

VikTech Fittings is a reputed manufacturer, exporter, and supplier of Lap Joint Flanges in compliance with ASME/ANSI B16.5, B16.47, and international standards. A Lap Joint Flange (LJ Flange) is designed to be used with a stub end fitting, where the flange is slipped over the pipe and the stub end is butt-welded to the pipe. The flange itself is not welded but rotates freely around the pipe and stub end, making alignment and dismantling easier.

What is a Lap Joint Flange?

A Lap Joint Flange is a two-component assembly consisting of a loose backing flange and a stub end. This design is highly beneficial for systems that require frequent dismantling, inspection, or cleaning, as the flange can be easily rotated to align bolt holes. Lap Joint Flanges are commonly used in low-pressure, non-critical, and corrosive environments.

Types of Lap Joint Flanges

• Raised Face Lap Joint Flange (RF-LJ)

• Flat Face Lap Joint Flange (FF-LJ)

• Stub End + Lap Joint Flange Assembly

• Custom-Made Lap Joint Flanges

Materials & Grades

✅ Carbon Steel Lap Joint Flanges

• ASTM A105 / A105N

• ASTM A350 LF2 (Low Temp)

• ASTM A694 F42 – F70

✅ Stainless Steel Lap Joint Flanges

• ASTM A182 F304 / 304L

• ASTM A182 F316 / 316L

• ASTM A182 F321 / F347

✅ Duplex & Super Duplex Steel Lap Joint Flanges

• UNS S31803 / S32205

• UNS S32750 / S32760

✅ Alloy Steel Lap Joint Flanges

• ASTM A182 F1, F5, F9, F11, F22, F91

✅ Nickel Alloys & Special Grades

• Inconel 600 / 625 / 800 / 825

• Monel 400 / K500

• Hastelloy C22 / C276

• Alloy 20

• Copper Nickel (Cu-Ni) 70/30, 90/10

• Titanium Gr.2 / Gr.5

Advantages of Lap Joint Flanges

• Easy alignment of bolt holes (rotatable)

• Cost-effective when used with corrosion-resistant stub ends

• Ideal for frequent dismantling & cleaning

• Less material cost as backing flange need not be corrosion resistant

• Suitable for low-pressure and non-critical applications

Applications of Lap Joint Flanges

• Chemical and food processing industries

• Desalination plants & water treatment

• Pharmaceutical plants

• Marine & offshore applications

• Low-pressure pipelines with frequent dismantling

• Corrosive environments with lined or clad pipes

Technical Specifications

Specification ItemDetailsStandardASME/ANSI B16.5, B16.47, MSS-SP44, DIN, EN 1092-1, JIS B2220, BS 4504Size Range½” (DN15) to 48” (DN1200)Pressure RatingClass 150, 300, 600, 900, 1500, 2500Facing TypesRF (Raised Face), FF (Flat Face)Stub EndsMSS-SP43, ASTM A403 BW Stub EndsTestingPMI, UT, Hydro Test, NDT, NACE MR0175, Third-Party InspectionCertificationEN 10204 3.1 / 3.2, ISO, CE