L&A forge lap joint flange

What are Lap Joint Flange ?

Lap Joint Flanges have all the same common dimensions as any other flange named on this page however it does not have a raised face, they used in conjunction with a “Lap Joint Stub End”.

These flanges are nearly identical to a Slip On flange with the exception of a radius at the intersection of the flange face and the bore to accommodate the flanged portion of the Stub End.

Their pressure-holding ability is little, if any, better than that of Slip On flanges and the fatigue life for the assembly is only one tenth that of Welding Neck flanges.

They may be used at all pressures and are available in a full size range. These flanges slip over the pipe, and are not welded or otherwise fastened to it. Bolting pressure is transmitted to the gasket by the pressure of the flange against the back of the pipe lap (Stub End).

Lap Joint flanges have certain special advantages:

  • Freedom to swivel around the pipe facilitates the lining up of opposing flange bolt holes.

  • Lack of contact with the fluid in the pipe often permits the use of inexpensive carbon steel flanges with corrosion resistant pipe.

  • In systems which erode or corrode quickly, the flanges may be salvaged for re-use.

Standard Specification For Stainless steel Lap Joint Flange:

  • Dimensions :ANSI B16.5, ANSI B16.47 Series A & B, MSS SP44, ASA, API-605, AWWA, Custom Drawings

  • Size :1/2″ (15 NB) to 48″ (1200NB)

  • Grades : 300, 301, 301L, 303, 304, 304L, 304H, 310, 310S, 310H, 310, 316L, 316H, 321, 321H, 347, 409, 410, 416, 430, 904L

  • Class :150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS, DIN Standard ND-6,10, 16, 25, 40 Etc.

  • DIN :DIN 2527, DIN 2566, DIN 2573, DIN 2576, DIN 2641, DIN 2642, DIN 2655, DIN 2656, DIN 2627, DIN 2628, DIN 2629, DIN 2631, DIN 2632, DIN 2633, DIN 2634, DIN 2635, DIN 2636,DIN 2637, DIN 2638, DIN 2673

  • BS : BS 4504 , BS 4504, BS 1560, BS 10

  • PN :PN6, PN10, PN16, PN25, PN40

  • Flange Face Type : Flate Face (FF), Ring Type Joint (RTJ)