Om Tubes& Fittings Industries
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Exploded view

Four parts.
One seal.

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The fitting, in detail

One fitting.
Six surfaces.

Scroll to travel into the part. Each component opens onto the material it is cut from, how it is machined, and the finish it is held to.

01

Full assembly

NUT, FRONT FERRULE, BACK FERRULE AND BODY. FOUR PARTS, ONE GAS-TIGHT JOINT — ALL FOUR MADE AND GAUGED IN HOUSE.

Tube OD
3 – 50 mm
Imperial
⅛" – 2"
Working pressure
to 6 000 psi
Temperature
−60 to 650 °C
End connections
Tube × NPT · BSPT · BSPP
Parts per fitting
4
Remakes
Gas-tight to 25
Test
100% helium leak

Governing standards

  • ASTM A479
  • ASME B1.20.1
  • ISO 8434-1
  • SAE J514
  • MSS-SP-99
  • NACE MR0175

Materials

316 / 316L dual certified · 304 / 304L · Duplex S31803 · Super duplex S32750 · Monel 400 · Inconel 625 · Alloy 825 · Titanium Gr 2

Om Tubes FULL ASSEMBLY
Component 0001
02

Compression nut

HEXAGON TURNED FROM BAR ON A SLIDING-HEAD LATHE. THREADS ROLLED, NOT CUT, SO THE GRAIN RUNS UNBROKEN AROUND THE ROOT.

Stock
316 bar to ASTM A479
Thread
Rolled, class 2B
Across flats
8 – 60 mm
Anti-gall
Silver plate 5 µm
Pull-up
1¼ turns from finger tight
Flank finish
Ra 0.8 µm
Marking
Heat code + size
Gauging
100% go / no-go

Governing standards

  • ASME B1.1
  • ASTM A479
  • ASTM B700
  • ISO 965
  • ASME B18.2.2
  • ASTM A967

Inspection

Thread ring gauge · Plating thickness · Across-flats · Hardness · Heat traceability

Om Tubes COMPRESSION NUT
Component 0002
03

Body forging

HOT FORGED FROM ROUND BAR SO THE GRAIN FLOWS AROUND THE BEND. BORE DRILLED, REAMED AND HONED. THE ELBOW IS FORMED, NEVER WELDED.

Stock
Hot-forged 316 bar
Grain flow
Unbroken through bend
Bore
Drilled · reamed · honed
Bore finish
Ra 0.4 µm
Concentricity
0.05 mm TIR
Wall, minimum
2.4 mm
Heat treatment
Solution annealed 1040 °C
Marking
Laser-etched heat number

Governing standards

  • ASTM A479
  • ASTM A182
  • ASME B16.11
  • ASTM A262 Prac. E
  • ASTM A967
  • EN 10204 3.1

Inspection

PMI on 100% · Bore profilometry · Dye penetrant · Grain-flow macro-etch

Om Tubes BODY FORGING
Component 0003
04

Male NPT thread

CUT ON THE SAME SETUP AS THE BORE, SO THE THREAD STAYS CONCENTRIC TO THE FLOW PATH. TAPER GAUGED ON EVERY PIECE, NOT ON A SAMPLE.

Standard
ASME B1.20.1 NPT
Alternatives
BSPT · BSPP · ISO 7-1 · SAE
Size
⅛" – 2"
Taper
1 : 16
Gauging
100% L1 ring
Concentricity to bore
0.08 mm TIR
Crest finish
Ra 1.6 µm
Leak test
Air under water, 100 psi

Governing standards

  • ASME B1.20.1
  • ISO 7-1
  • ISO 228-1
  • BS 21
  • DIN 2999
  • JIS B0203

Inspection

L1 ring gauge · Thread profile projector · Air-under-water · Torque-to-seal

Om Tubes MALE NPT THREAD
Component 0004
05

Front & back ferrule

THE FRONT SEALS AGAINST THE BODY CONE, THE BACK COLLETS ONTO THE TUBE WALL. CASE HARDENED TO BITE WITHOUT PICKING UP.

Material
316, case hardened
Case depth
0.05 – 0.10 mm
Surface hardness
800 – 1 000 HV
Core hardness
160 – 190 HV
Action
Two-point, colleting
Grip
Live spring-back on tube
Concentricity
0.02 mm TIR
Traceability
Per heat, per batch

Governing standards

  • ASTM A479
  • ASTM A967
  • ISO 8434-1
  • NACE MR0175
  • ASTM E384
  • EN 10204 3.1

Inspection

Micro-hardness traverse · Case-depth section · Profile projector · Pull-out test

Om Tubes FRONT & BACK FERRULE
Component 0005
06

Surface & finish

EVERY WETTED SURFACE PASSIVATED AND MEASURED ON A PROFILOMETER. NO SEAMS, NO TOOL CHATTER, NO FREE IRON.

Standard finish
Ra ≤ 0.8 µm
Electropolished
Ra ≤ 0.4 µm
Wetted bore, option
Ra ≤ 0.25 µm
Passivation
ASTM A967, nitric
Free iron
Ferroxyl negative
Seams & laps
None permitted
Appearance
10× visual, no chatter
Measurement
Contact profilometer

Governing standards

  • ASTM A967
  • ASTM A380
  • SEMI F19
  • ASME BPE
  • ISO 4287
  • ISO 21920

Inspection

Profilometer · Ferroxyl test · Copper sulphate · 10× visual · Passivation certificate

Om Tubes SURFACE & FINISH
Component 0006

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