4130 fittings
4130 reducers: concentric and eccentric
Concentric and eccentric reducers in AISI 4130, made seamless to ASME B16.9 lengths with the wall at each end matched to its pipe.
4130 reducers join two sizes of high-pressure line. A concentric reducer keeps both ends on one centerline; an eccentric reducer keeps one side flat. We make them seamless in AISI 4130 to ASME B16.9 lengths, with the wall or bore at each end matched to its pipe, for 7,500 to 15,000 psi lines.
Concentric or eccentric
| Type | Shape | Typical place |
|---|---|---|
| Concentric | Cone on one centerline | In-line size changes in manifolds and lines |
| Eccentric, flat side up | Top of pipe level | Pump suction, so no gas pocket forms |
| Eccentric, flat side down | Bottom of pipe level | Racks, and lines where solids should drain through |
ASME B16.9 reducer lengths
| Large end, NPS | Length, H |
|---|---|
| 1 | 2.00 (51) |
| 1-1/2 | 2.50 (64) |
| 2 | 3.00 (76) |
| 2-1/2 | 3.50 (89) |
| 3 | 3.50 (89) |
| 4 | 4.00 (102) |
| 5 | 5.00 (127) |
| 6 | 5.50 (140) |
| 8 | 6.00 (152) |
In ASME B16.9 the length depends on the large end only, so a 4 x 3 and a 4 x 2 reducer are both 4.00 in long.
Matching the wall at each end
A reducer joins two pipes that may not share a schedule, so each end is made to its own pipe. A 4 x 3 in reducer can be XXS on both ends, or XXS on the large end and Sch 160 on the small end, or two heavy-wall sections ordered by OD and ID, such as 5.5 in OD by 3 in ID down to 3.5 in OD by 2.3 in ID. The cone between them keeps at least the wall needed for the higher-pressure end. Give the wall or bore for each end on the order.
Heat treatment and pressure
A reducer is rated as straight seamless pipe of the same material and wall, the rule ASME B16.9 uses for every butt-weld fitting, so its rating follows the weaker of its two ends and the strength level ordered. See pressure ratings for 4130 pipe and fittings. For sour service, order 22 HRC maximum with a hardness survey.
Ordering
Concentric reducer, 4 x 3 in, large end XXS, small end Sch 160, ASME B16.9, AISI 4130 quenched and tempered, 75 ksi min yield, 95 ksi min tensile, 22 HRC max, EN 10204 3.1, 4 pcs
Frequently asked questions
Concentric or eccentric?
Concentric for most in-line size changes. Eccentric where one side of the line must stay level: flat side up at a pump suction so no gas pocket forms, flat side down where the bottom of the pipe must stay level, for example on a rack or where solids should drain through.
Can the two ends have different walls?
Yes. Each end is made to its own pipe, for example XXS on the large end and Sch 160 on the small end, or two OD by ID sections. State the wall or bore for each end.
Is a reducer the same as a swage?
Not quite. A butt-weld reducer is a short fitting with the lengths of ASME B16.9. A swage nipple is longer and usually has plain, threaded or socket ends. For welded 4130 lines, order a reducer unless your drawing calls for a swage.