Threaded pipe fittings refer to pipe fittings connect with pipes by internal or external threads and their dimensions are no more than 4 inch in most cases. Thread connection is the oldest way that we still use today.

Most of forged threaded fittings are specified in ASME B16.11, including threaded elbow, threaded tee, half and full coupling, threaded cap, hex nipple, bushing and plug. ASME B16.11 is an American standard which popular internationally.

In addition to this, there are other common used standards and fittings such as BS 3799 threaded fittings, MSS-SP-97 threadolet, MSS-SP-83 union and ASME B36.19 nipple.

Threaded Pipe Fittings Catalogue

Threaded Elbow

It is shorten as THD elbow sometimes. Threaded elbow is used to connect pipe and change the directions of flow in 90 degree or 45 degree. The dimension of two end could be equal or reducing.

Threaded Tee

This threaded fittings has three outlets in same or different diameter. Like threaded elbows, branch in same diameter called equal / straight tee otherwise it is reducing tee.

Threaded Cap

The function of threaded caps is block off the flow at the end of pipes. It is also available in socket weld and buttweld end, pipe elbow and pipe tee as well.

Threaded Coupling

It is a short pipe with internal threaded at one end or both end. The former is half coupling and the latter is full coupling. The other end of half coupling will weld to pipes. This threaded pipe fitting also has reducing type.

Threaded Union

This threaded pipe fittings has the function to connect and adapt the diameter of pipes, but different with pipe coupling for allowing disconnection of the pipes for maintenance.

Threaded Nipple

Threaded nipple can be further divided into hex nipple, barrel nipple, close nipple and welding nipple, its function is similar as coupling and union.

Bushing

Bushing and plug are only available in threaded type. This threaded pipe fitting has male and female threads to connect pipes together.

Plug

Plug is a male threaded pipe fittings to stop pipe flow at the end. It has hex head, round head and square head three types.

Threadolet

Threadolet is a integrally reinforced branch outlet fittings which can offer branches from pipe header.

Thread Types of Forged Threaded Pipe Fittings

The threads are also available in different types, the most prevalent types are NPT, BSPP and BSPT.

NPT is the standard threads type for ASME B16.11 threaded pipe fittings, it is a tapered thread with 60°angles. Its connection requires the help of sealant.

BSPP is British standard parallel threads, its sealing requires a seal ring. BSPP threaded pipe fittings are popular in Asia, Europe, Australia and South Africa.

BSPT is also a British threads, but it is tapered with 55°angles. BSPT and BSPT belong to BSP threads, but they cannot use together.

Applications of ASME B16.11 Forged Fittings

Forged threaded pipe fittings can withstand high pressure up to class 6000, however, due to socket weld fittings have better leap-proof than threaded fittings, threaded fittings are more prevalent in lower pressure ratings. They are suitable for pipe system where welding is difficult to operate.

ASME B16.11 Threaded Pipe fittings are widely used in

• Oil and Gas
• Chemical
• Power station
• Shipbuilding
• Aerospace constructions

Advantages and Disadvantages of Threaded Fittings

Advantages

• Simple usage
• Easy installation
• Able to disconnection and convenient maintenance

Disadvantages

• Prone to leak due to rapid temperature changes
• Vibration and hazardous pipe system is not suit for threaded pipe fittings because they prone to be fatigue damaged.

Material Grades for Forged Steel Fittings

Stainless Steel Forged Threaded Fittings

ASTM A182 F304, F316, F310, F321, F309, F317

Carbon steel Forged Threaded Fittings

ASME A105, A350 LF/LF3, A106 A/B/C, API 5L, API 5L GR. B, API 5L X 42, X 46, X 52, X 60, X 65 & X 70.

Alloy Steel Forged Threaded Fittings

ASTM A182 F1, F5, F9, F11, F12, F22, F91

Duplex Stainless Steel Forged Threaded Fittings

ASTM A182 F51, F53, F55 / UNS S31803, S32205, S32550, S32750, S32950

Nickel Alloy Forged Threaded Fittings

UNS2200 (NICKEL 200) , UNS2201 (NICKEL 201 ) , UNS4400 (MONEL 400 ), UNS8825 (INCONEL 825) , UNS6600 (INCONEL 600 ) , UNS6601 (INCONEL 601) , UNS6625 (INCONEL 625) , UNS10276 (HASTELLOY C 276)

Copper Alloy Forged Threaded Fittings

UNS NO. C 70600 ( CU -NI- 45/10) , C 71500 ( CU -NI- 70/30), C 10100 , C 10200 , C 10300 , C 10800 , C 12000, C 12200

ASME B16.11 Threaded Fittings Weight Chart