Piping Materials : Threaded Fittings

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Pros

Threaded joints can be easily made from pipe and fittings on site. They minimize fire hazard when installing in areas where flammable gases and liquids are present.

Cons

Use of threaded joints is not permitted by ANSI B31.1 if sever erosion, crevice corrosion, shock or vibration is anticipated, nor at temperatures over 925 F. Chances of leakage are high with threaded joints. Seal welding may be required in more risky situations. For threaded joints, strength of pipe is reduced as forming the screw thread reduces the wall thickness.

Applications

Threaded fittings are used for conveying services and for smaller process piping.

Fittings

Major available fittings are :

  1. 90 deg. LR Elbow
  2. 45 deg. LR Elbow
  3. Caps
  4. Straight and Reducing Tees
  5. Straight Cross
  6. Full Coupling
  7. Half Coupling
  8. Reducing Coupling
  9. Barstock plug,
  10. Close nipples,
  11. TBE nipple,
  12. POE-TOE nipple,
  13. Tank Nipple,
  14. Pipe to tube connector,
  15. Hexagon bushing
  16. Unions
  17. No such Fittings : Short Radius elbows, returns, bends and reducers are not available in B16.11.
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90 deg. LR Elbow

Available size range is from 1/8″ to 4″ as per ASME B16.11.

45 deg. LR Elbow

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Caps

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Straight and Reducing Tees

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Straight Cross

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Full Coupling

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Half Coupling

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Reducing Coupling

Available size range is from 1/8″ to 4″ as per ASME B16.11.

barstock plug

Available size range is from 1/8″ to 4″ as per ASME B16.11.

close nipples

OD is as per standard pipe dimensions. Length is as per project requirement.

TBE nipple

OD is as per standard pipe dimensions. Length is as per project requirement.

POE-TOE nipple

OD is as per standard pipe dimensions. Length is as per project requirement.

Tank Nipple

Tank nipple is used for making a screwed connection to a non-pressure vessel or tank in low pressure service.

Pipe to tube connector

Typical use is  to connect instrumentation tubes to Air Pipes. Also used for Analyser Tubing.

Hexagon bushing

Available size range is from 1/8″ to 4″ as per ASME B16.11.

Unions

Unions permits easy installation, removal or replacement of lengths of pipe, valves or vessels in screwed piping systems. To remove a valve it must have at least one adjacent union and to remove piping from a vessel with threaded connections, each outlet from the vessel should have one union between valve and vessel.

Inside Union, ground faced joints are preferred, although other facings are available.

Reducing Insert

Reducing insert is used for connecting a small pipe to a larger fitting.

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Ratings

Ratings for Threaded Fittings are Class 2000, 3000, 6000. Choice of Class depends on thickness schedule of pipe, as given in ASME B16.11.

  1. Class 2000 for Sch80 and XS,
  2. Class 3000:Sch 160, 6000:XXS

Size Range

Threaded fittings are available upto 4” as per ASME B16.11.

Materials of Construction

These fittings are forged fittings. So Materials of Construction are as follows.

Materials of Construction for Forged Piping Fittings

Sample Piping Material Specification

Elements : 45 Degree elbow, 90 Degree elbow, Equal Tee, Reducing Tee, Caps, Full Coupling, Reducing Coupling

  1. Material : CS : ASTM A105. Galvanised, NIC, HIC as per spec.
  2. Material : SS : ASTM A182 F304L
  3. Threaded : 2000:Sch80 and XS, 3000:Sch 160, 6000:XXS
  4. Ends : Threaded Female Ends,
  5. Dim Standard : ASME B16.11

Elements : Pipe to Tubing Adapter

  1. Material : CS:ASTM A105,
  2. Class : NA,
  3. Ends : Female threaded end / Compression twin ferrule, Dim Standard : Manufacturer.

Elements : Hex Head Bushing

  1. Material : CS : ASTM A105,
  2. Ends : Threaded Male / Threaded Female Ends.,
  3. Standard : ASME B16.11

Elements : Concentric Swage, Eccentric Swage

  1. Material : CS : Made from seamless pipe ASTM A234 Gr. WPB
  2. Material : SS : Made from seamless pipe ASTM A403 Gr. WP304LS
  3. Ends : Threaded Both Ends, Standard : BS3799

Element : Round Head Plug

  1. Material : CS : ASTM A105,
  2. Ends : Threaded Male Ends,
  3. Standard : ASME B16.11

Element : Union

  1. Material : CS : ASTM A105,
  2. Class : 3000,
  3. Ends : Compression Twin Ferrule both Ends,
  4. Standard : Manufacturer Standard

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