"SAE" flanges are manufactured in accordance with the mounting dimensions and O-Rings of SAE J518 specifications, either Code 61 or Code 62, and ISO 6162. Stock flanges include socket weld, butt weld, NPTF and SAE straight thread connections and are available as reducers, in-line & elbows.

Companion (flat-faced) flanges, for unions or converting split flange connections to pipe and tubing, are available with either inch or metric threads.
As already before described, the most used flange types acc. to ASME B16.5 are: Welding Neck, Slip On, Socket Weld, Lap Joint, Threaded and Blind flange.


Welding Neck Flanges are easy to recognize at the long tapered hub, that goes gradually over to the wall thickness from a pipe or fitting.

The long tapered hub provides an important reinforcement for use in several applications involving high pressure, sub-zero and / or elevated temperatures. The smooth transition from flange thickness to pipe or fitting wall thickness effected by the taper is extremely beneficial, under conditions of repeated bending, caused by line expansion or other variable forces.

These flanges are bored to match the inside diameter of the mating pipe or fitting so there will be no restriction of product flow. This prevents turbulence at the joint and reduces erosion. They also provide excellent stress distribution through the tapered hub and are easily radiographed for flaw detection.

This flange type will be welded to a pipe or fitting with a single full penetration, V weld (Buttweld).


The calculated strength from a Slip On flange under internal pressure is of the order of two-thirds that of welding neck flanges, and their life under fatigue is about one-third that of the latter.

The connection with the pipe is done with 2 fillet welds, as well at the outside as also at the inside of the flange.

The X measure on the image, are approximately:
Wall thickness of pipe + 3 mm.

This space is necessary, to do not damage the flange face, during the welding process.

A disadvantage of the flange is, that principle always firstly a pipe must be welded and then just a fitting. A combination of flange and elbow or flange and tee is not possible, because named fittings have not a straight end, that complete slid in the Slip On flange.

Socket Weld FLANGE

Socket Weld flanges were initially developed for use on small-size high pressure piping. Their static strength is equal to Slip On flanges, but their fatigue strength 50% greater than double-welded Slip On flanges.

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.

Stub End

A Stub End always will be used with a Lap Joint flange, as a backing flange.
This flange connections are applied, in low-pressure and non critical applications, and is a cheap method of flanging.
In a stainless steel pipe system, for example, a carbon steel flange can be applied, because they are not come in contact with the product in the pipe.

Stub Ends are available in almost all pipe diameters. Dimensions and dimensional tolerances are defined in the ASME B.16.9 standard. Light-weight corrosion resistant Stub Ends (fittings) are defined in MSS SP43.

Threaded Flanges are used for special circumstances with their main advantage being that they can be attached to the pipe without welding. Sometimes a seal weld is also used in conjunction with the threaded connection.


Blind Flanges are manufactured without a bore and used to blank off the ends of piping, valves and pressure vessel openings.
From the standpoint of internal pressure and bolt loading, blind flanges, particularly in the larger sizes, are the most highly stressed flange types.

However, most of these stresses are bending types near the center, and since there is no standard inside diameter, these flanges are suitable for higher pressure temperature applications.
  • Confirms to SAE, DIN, CETOP, BS & ASA
  • Wide Range : CODE 61/62 [3000 & 6000class], Split, Socket Weld, Butt Weld,
  • Threaded, Reducer & Conversion Flanges.

  • Material : Steel, S.S.304 & S.S.316
    Surface Treatment : Zinc Coated & Bi Chromated [A3C TO ISO 4042] or Phosphates or as per customer requirements

Petroleum Industry, Fertiliser Industry, Engineering Industry, Pipeline & Water Line Pressure vessels.

Technical Specification

Size Range 1/2” NB to 72” NB
Class 150 LBS to 2500 LBS
Material ASTM A-105, A-182, F-304 / 304L / 316 / 316L / 321, A-350LF-1, LF-2, LF3, A-182 Gr. F-1, F-5, F-9, F-11, F- 12, F-22
Specifications ANSI B -16.5, DIN , BS , JIS , AWWA , B16.47 , API AND MSSSP44


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