Чем концентрический переход отличается от эксцентрического?

У концентрического общая ось обоих концов; у эксцентрического оси смещены (общая образующая) — это удобно на горизонтальных участках для отвода конденсата или воздуха.

Как обозначается типоразмер?

Парой диаметров: больший × меньший, например 108×57 (или Ду100×Ду50).

Штампованный или сварной?

До Ду400 — бесшовные штампованные; для больших диаметров — сварные (лепестковые).

Из каких сталей?

Ст20, 09Г2С, 12Х18Н10Т и другие по проекту.

Как присоединяется?

Сваркой встык к трубам обоих диаметров.

Concentric steel transition according to ГОСТ 17378

Specifications

Technical parameters

Item	Steel transition (concentric/eccentric)
Type	Concentric, eccentric
Nominal bore DN	25-1420 mm
Manufacturing	Stamped (seamless), welded
Wall thickness	2.0–20 mm (through the pipe)
Material	Ст20, 09Г2С, 12Х18Н10Т and others .
Connection	For butt welding
Standards	ГОСТ 17378-2001 (ISO 3419)
Pressure	up to PN 160
Temperature	−70…+450 °C
Medium	Water, steam, petroleum products, gas, aggressive media

Dimension diagram

Drawing to GOST

The letters on the diagram correspond to the columns of the dimension table below.

Dimensions

Dimension table

Ду×Ду1	D, mm	D1, mm	L, mm
25×20	33,7	26,9	51
32×25	42,4	33,7	51
40×32	48,3	42,4	64
50×40	60,3	48,3	76
65×50	76,1	60,3	76
80×65	88,9	76,1	89
100×80	114,3	88,9	102
125×100	139,7	114,3	127
150×125	168,3	139,7	140
200×150	219,1	168,3	152
250×200	273,0	219,1	178
300×250	323,9	273,0	203
350×300	355,6	323,9	330
400×350	406,4	355,6	356
500×400	508,0	406,4	381
600×500	610,0	508,0	508

D is the outer diameter of the larger end, D1 is the smaller one, and L is the face length. Values according to ГОСТ 17378-2001 (harmonized with ISO 3419 / ASME B16.9). Eccentric transitions and intermediate pairs are available on request.

Kinds

Types of transitions

Concentric

The common axis of entry and exit is for vertical and common sections.

Eccentric

Offset axis (common generating axis) — for horizontal sections with condensate/gas discharge.

Stamped

Seamless stamped according to ГОСТ 17378, DN up to 400.

Welded (lobed)

For large diameters DN 500-1420 by ГОСТ 17378/ТУ.

Materials

Steel grades

Ст2009Г2С15ХМ12Х18Н10Т10Х17Н13М2Т

Applications

Where they are used

Connecting pipes of different diameters
Tie-ins, pump assemblies, and fittings
Heating networks, steam, oil and gas, water supply

Order

What to state when ordering

A pair of diameters Ду×Ду1 (or D×D1 × wall thickness)
Type: Concentric / Eccentric
Steel grade and ГОСТ
Coating/insulation if necessary

Questions

Frequently asked questions

How does a concentric transition differ from an eccentric one?

The concentric one has a common axis at both ends; the eccentric one has an offset axis (a common generatrix) — this is convenient in horizontal areas for condensate or air drainage.

How is the standard size indicated?

A pair of diameters: larger × smaller, for example 108×57 (or Ду100×Ду50).

Stamped or welded?

Up to Ду400 — seamless stamped; for large diameters — welded (lobed).

What kind of steels?

Ст20, 09Г2С, 12Х18Н10Т and others on the project.

How does it join?

Butt welding to pipes of both diameters.

The transition is concentric