B16.5 Carton Steel Welding Neck Flange

Bangdong Supply A182 F51 Flanges,A182 F304L Flanges,A182 F91 Flanges.Early carbon steel flange producers employed a manufacturing method called butt-welding. The butt-welding process was quite elementary in that it merely rolled a piece of  heated steel plate into tubular form and created a longitudinal weld through compression and direct heat. When the mill came to the end of a coil, they could simply weld it to the beginning of the next coil with little interruption to production.

MOST COMMON FLANGE TYPES

Welding Neck 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).

DETAILS OF WELDING NECK FLANGE

1. Weld Neck flange 2. Butt Weld
3. Pipe or Fitting

Slip On flange

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.

DETAILS OF SLIP ON FLANGE

1. Slip On flange 2. Filled weld outside
3. Filled weld inside 

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.

LAP JOINT FLANGE WITH A STUB END

Threaded flange

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.

Although still available in most sizes and pressure ratings, screwed fittings today are used almost exclusively in smaller pipe sizes.

A threaded flange or fitting is not suitable for a pipe system with thin wall thickness, because cutting thread on a pipe is not possible. Thus, thicker wall thickness must be chosen...what is thicker ?

ASME B31.3 Piping Guide says:
Where steel pipe is threaded and used for steam service above 250 psi or for water service above 100 psi with water temperatures above 220° F, the pipe shall be seamless and have a thickness at least equal to schedule 80 of ASME B36.10.

DETAILS OF THREADED FLANGE

1. Threaded flange 2. Thread 3. Pipe or Fitting

Blind flange

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.

DETAILS OF BLIND FLANGE

1. Blind flange 2. Stud Bolt 3. Gasket 4. Other flange