Compression Tube Fittings
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37 Degree Flare Fittings - General Information

37 Degree Flare Fittings

Introduction
A 37-flare fitting is an excellent pressure fitting having a broad selection of styles & shapes and is very extensively used all over the globe. Main features that call for its use are its simplicity, compactness in design, ease of assembly, high reliability, easy availability & global acceptance. These flare fittings can also be used as hose adapters.

The basic design is simple, which uses a flared tube end to hold & seal the medium under pressure. Main construction consists of three pieces: the body, sleeve & nut. The end of the tube is flared to 74 degrees included angle and held in between the body nose and the sleeve with a nut on top of them, thus resulting in a very effective seal between the fittings and the flared tube.

Straight flare fitting are normally manufactured from cold drawn bar stocks and all angular fittings from forgings. This kind of forged construction results in very close grain structure and also gives high reliability to the fitting eliminating all possibilities of leakage and can withstand high pressures with numerous makes and remakes even under severe operating conditions.

Also these fittings can be easily used in both metric and inch tubing's. One single 37 degree fitting body can take both metric and inch tubes just by change in sleeves. The nuts used are the same, so the cost of the component comes down drastically and also the inventory.



Range:
Ranges of 37 flare fitting manufactured are in between 1/4" to 1 ½" and in metric tubing from 6mm to 38mm.



SD Industries are manufacturer and supplier of flare fittings, compression flare fittings, compression fittings, hydraulic fittings and many more. These flare fittings can also be used as hose adapters. Main features that call for its use are its simplicity, compactness in design, ease of assembly, high reliability, easy availability & global acceptance.



Features:
The 37 degree flared tube fittings manufactured by us provide leakproof, full flow connections in hydraulic systems operating at working pressures as specified in the tables below.


Thread Size Working Pressures
Nom Inch Tube O.D. SAE J514 Flared Tube End and SAE J1926/3/ ISO 11926-3 O-Ring Port Thread Size (Notes 1&2) 37 Deg. Flared Tube Ends, Unions and Bulkheads. 37 Deg. Female Swivels.
    MPa psi MPa psi
1/8 5/16-24 UNF 34.5 5,000 34.5 5,000
3/16 3/8-24 UNF 34.5 5,000 34.5 5,000
1/4 7/16-20 UNF 34.5 5,000 31 4,500
5/16 1/2-20 UNF 34.5 5,000 27.5 4,000
3/8 9/16-18 UNF 34.5 5,000 27.5 4,000
1/2 3/4-16 UNF 31 4,500 27.5 4,000
5/8 7/8-14 UNF 24 3,500 21 3,000
3/4 1-1/16-12 UN 24 3,500 21 3,000
7/8 1-3/16-12 UN 21 3,000 17 2,500
1 1-5/16-12 UN 21 3,000 17 2,500
1 1/4 1-5/8-12 UN 17 2,500 14 2,000
1 1/2 1-7/8-12 UN 14 2,000 10.5 1,500
2 2-1/2-12 UN 10.5 1,500 8 1,125


1. Threads per SAE J475 Class 2A ext. Class 2B int. (Ref. ISO-263/ISO-R725)
2. Unified class 2B threads apply to swivel nuts and with minor diameter modified to class 3B limits for locknuts


Thread Size Working Pressures
Nom Inch Pipe O.D. Dryseal Pipe Thread (NPTF) Male and Female Fittings With NPTF Pipe Threads
    MPa psi
1/8 1/8-27 34.5 5,000
1/4 1/4-18 27.5 4,000
3/8 3/8-18 21 3,000
1/2 1/2-14 21 3,000
3/4 3/4-14 17 2,500
1 1-11-1/2 14 2,000
1 1/4 1-1/4-11-1/2 8 1,150
1 1/2 1-1/2-11-1/2 7 1,000
2 2-11-1/2 7 1,000


1. Dryseal American Standard Taper Pipe Thread

A huge variety of fitting styles are available that allow connection of flared tube ends, machined male or female 37 degree ends or male or female NPTF pipe or hose ends. Also included in this section are low-pressure beaded hose stem fittings.

37 degree-flared fittings are the most commonly used tube connections, internationally. Tube preparation and flaring processes are easily accomplished with either hand or power tools. The large variety of fitting configurations and jump sizes available provide for simplified fabrication requirements and reduced parts count in complex systems.

The design of the 37-degree flared fitting tube end is identical for either inch or metric tubing. With the exception of stock size, the flared tube fittings described in this section are interchangeable with equivalent fitting styles (unions, bulkheads, tees, etc.) per ISO 8434-2.

All 37-degree fitting styles are also available with the optional flare tube end design.



Performance:
Where applicable, fittings are designed and qualified to the requirements of SAE J514. Beaded hose stem ends conform to SAE J1231 and are intended for suction or low pressure lines, typically less than 300 PSI.



Construction:
Stainless steel fittings are machined from 316 stainless steel barstock or forgings. Fittings are passivated followed with machining.



Threads:
Straight Threads: Internal and external straight threads conform to the Unified National Class 2A and Class 2B Series respectively, with modified minor diameters where specified.

NPTF Threads: Male and female pipe threads conform to the Dryseal American Standard Taper Pipe Thread (SAE J476a, NPTF) Series which will provide pressure tight joints without the use of a lubricant or sealer. Use of these fittings with non-dryseal NPT pipe or hose ends is not recommended for high-pressure applications. Note: Where not functionally objectionable, use of a compatible lubricant/sealant is recommended for either NPT or NPTF threads to minimize the possibility of galling in assembly.



Assembly Information :
Tubing for single flare tube ends should be either seamless or welded and drawn, fully annealed tubing per ASTM A213, ASTM A249 or ASTM A269 respectively.

For proper sealing with 37 degree flared fittings, flares for tubing should conform to the requirements of SAE J533. For heavy wall tubing, the optional tube preparation and single flare configuration specified in SAE J533 is also recommended. This optional configuration provides extended sealing surface contact area versus conventional flares.

In the design and fabrication of tubing or hose runs for any hydraulic system, precautions should be taken to allow for sufficient adjustment of the hose or tubing so that proper alignment can be attained at the fitting connections. Improper fit-up or misalignment should be corrected before final connections are made. Location of fitting connections should be planned to maximize accessibility. Whenever possible, use a torque wrench to tighten connections to the recommended installation torque.


Table ST1. Pressure Ratings for 37 Deg. Flared Tube Ends, Unions, Bulkheads and 37 Deg. Female Swivels
Nominal Tube Size Thread Size Working Pressures
Nom Inch
Tube O.D.
SAE J514 Flared Tube End and SAE J1926/3/ ISO 11926-3 O-Ring Port Thread Size (Notes 1&2) 37 Deg. Flared Tube Ends, Unions and Bulkheads 37 Deg. Female Swivels
    MPa psi MPa psi
1/8 5/16-24 UNF 34.5 5,000 34.5 5,000
3/16 3/8-24 UNF 34.5 5,000 34.5 5,000
1/4 7/16-20 UNF 34.5 5,000 31 4,500
5/16 1/2-20 UNF 34.5 5,000 27.5 4,000
3/8 9/16-18 UNF 34.5 5,000 27.5 4,000
1/2 3/4-16 UNF 31 4,500 27.5 4,000
5/8 7/8-14 UNF 24 3,500 21 3,000
3/4 1-1/16-12 UN 24 3,500 21 3,000
7/8 1-3/16-12 UN 21 3,000 17 2,500
1 1-5/16-12 UN 21 3,000 17 2,500
1 1/4 1-5/8-12 UN 17 2,500 14 2,000
1 1/2 1-7/8-12 UN 14 2,000 10.5 1,500
2 2-1/2-12 UN 10.5 1,500 8 1,125
1) Threads per SAE J475 Class 2A ext. Class 2B int. (Ref. ISO-263/ISO-R725)
2) Unified class 2B threads apply to swivel nuts and with minor diameter modified to class 3B limits for locknuts


Table ST2. Pressure Ratings for Fittings With NPTF Pipe Threads
Nominal Pipe Size Thread Size Working Pressures
Nom Inch
Pipe O.D.
Dryseal Pipe Thread (NPTF1) Male and Female Fittings With NPTF Pipe Threads
    MPa psi
1/8 1/8-27 34.5 5,000
1/4 1/4-18 27.5 4,000
3/8 3/8-18 21 3,000
1/2 1/2-14 21 3,000
3/4 3/4-14 17 2,500
1 1-11-1/2 14 2,000
1 1/4 1-1/4-11-1/2 8 1,150
1 1/2 1-1/2-11-1/2 7 1,000
2 2-11-1/2 7 1,000
1) Dryseal American Standard Taper Pipe Thread