Cast austenitic stainless steel threaded fittings - elbows, tees, sockets, nipples, bushes, caps, plugs and unions - in sizes 1/8 to 4 (DN6 to DN100). ISO 4144:2003 specifies the type and rates it at 20 bar non-shock at ambient.
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Cast stainless steel threaded fittings are the low-pressure screwed range used on instrument, service water, compressed air and light process lines. ISO 4144:2003 is the international standard for them: it specifies the types, pressure-temperature ratings, minimum dimensions and materials of stainless steel fittings threaded in accordance with ISO 7-1, for ordinary piping carrying steam, air, media, water or oil.
The rating is modest and falls with temperature. ISO 4144 Table 2 gives a non-shock maximum working pressure of 20 bar from -20 to 40 degrees C, 16,5 bar at 100 C, 15 bar at 150 C, 14 bar at 200 C and 13,5 bar at 220 C, with intermediate temperatures taken by interpolation. Sizes run from 1/8 to 4 (DN6 to DN100), and the standard fixes a minimum wall thickness for each size, from 1,5 mm at the small end to 4,1 mm at size 4 in cast material.
ISO 4144 threads are to ISO 7-1 and are tapered 1:16, although internal threads may be parallel; union nuts and their mating threads follow the ISO 68-1, ISO 228-1 and metric series instead. Twelve types are covered: equal and reducing elbows, 45 degree elbows, male-and-female elbows, equal and reducing tees, crosses, half sockets, equal and reducing sockets, reducing bushes, equal and reducing hexagon nipples, caps, plugs, and unions with either a flat or a taper seat. Material is austenitic stainless steel with a proof stress at least equal to steel TS 47 of ISO 2604-2, solution annealed to ISO 4991.
When ordering, state the fitting type; the size, and both sizes for a reducing fitting; the thread form - BSP taper, BSP parallel or NPT - which the "150" class mark cast into these bodies does not settle, and whether male or female; the grade required, 304 or 316; and the working pressure and temperature. These are not high-pressure fittings. Where the duty exceeds the ISO 4144 table, a forged fitting to ASME B16.11 is the correct part.
| Standard | ISO 4144:2003 - Pipework, stainless steel fittings threaded in accordance with ISO 7-1, for ordinary piping for steam, air, media, water, oil |
|---|---|
| Pressure-Temperature Rating (ISO 4144) | Non-shock maximum working pressure: 20 bar from -20 to 40 C, 16,5 bar at 100 C, 15 bar at 150 C, 14 bar at 200 C, 13,5 bar at 220 C. Intermediate temperatures by interpolation |
| Size Range (ISO 4144) | Thread sizes 1/8, 1/4, 3/8, 1/2, 3/4, 1, 1.1/4, 1.1/2, 2, 2.1/2, 3 and 4 (DN6 to DN100) |
| Threads | ISO 4144 fittings are threaded to ISO 7-1, tapered 1:16, with parallel internal threads permitted; union nuts and their mating threads follow ISO 68-1, ISO 228-1, ISO 261, ISO 262 or ISO 724. The form actually cut on this stock is not determinable from the photograph and is not stated in the catalogue record, so specify BSP taper (ISO 7-1), BSP parallel (ISO 228-1) or NPT (ASME B1.20.1) on order. These are not interchangeable |
| Material | Austenitic stainless steel with proof stress at least equal to that of steel TS 47 of ISO 2604-2, solution-annealed to ISO 4991:1994 cl. 5.2 Table 1. Fittings may be cast, rolled or forged |
| Fitting Types | Twelve types: equal and reducing elbows (E1, E2), 45 degree elbows (E3), male-and-female elbows (E4), equal and reducing tees (T1, T2), crosses (X1), half sockets (S1), equal and reducing sockets (S2, S3), reducing bushes (B1), equal and reducing hexagon nipples (N1, N2), caps (C1), plugs (P1, P2), unions with flat seat (U1-U3) and taper seat (U4-U6) |
| Minimum Wall Thickness (ISO 4144) | Cast material: 1,5 mm at 1/8 to 3/8; 1,6 mm at 1/2; 1,7 mm at 3/4; 1,9 mm at 1; 2,2 mm at 1.1/4; 2,4 mm at 1.1/2; 2,7 mm at 2; 3,2 mm at 2.1/2; 3,6 mm at 3; 4,1 mm at 4. Non-cast material may be reduced to 0,8 of these values |
| Class Marking on the Items Photographed | "150" and "3/4-150" cast into the bodies - the low-pressure 150 lb class designation for cast threaded fittings, and the size. Neither is a part number |
