Duplex Rod Axial Expansion Joint

Duplex rod axial expansion joint is a kind of compensator with large compensation capacity and simple structure, whose main structure consists of two (or more than two) bellows and short intermediate receiver and guide rod, which has bending resistance and guiding performance, and is capable of absorbing the axial displacement of the pipeline and ensuring that the bellows are not destabilized when working. They are usually used in pipelines with low fatigue frequency that require large compensation.

Overview

Application

Duplex rod axial expansion joint is generally used in low fatigue times of pipelines which need large compensation quantity, such as places with complex geological conditions, large settlement and frequent hot and cold changes in pipeline operation. Its simple structure and large compensation quantity are especially suitable for such occasions requiring large displacement compensation.

Installation and maintenance

(1) Check the nameplate: before installation, it is necessary to check whether the nameplate of the compensator is in accordance with the provisions of the construction drawings, and to check the appearance of the compensator.

(2) Adjust the limit nuts: after installation, the limit nuts at both ends should be adjusted to the rated compensation value or a little larger, but not removed.

(3) Installation direction: when equipped with liner cylinder, its direction should be the same as the medium flow direction (there is a flow direction sign on the expansion joint).

(5) Fixing nut: after installation on site, the nuts on both sides of the directional lugs must be backed up to the limiting nut. ‌

Nominal Diameter DN mm	Bellows		Axial compensation X₀ mm	Axial stiffness K_x0 N/mm	Radial shape Maximum size B mm	Product Length L mm		Product Type
	Wavenumber n	Effective area A cm²				Connection mode
	Wavenumber n	Effective area A cm²				Take over J	Flange F
Design pressure Pd=0.6MPa (6kgf/cm²) Fatigue life [N]=200 Design temperature t=20℃
80	20	108	127	69	290	900	910	FZ
100		145	126	80	310
125		205	123	95	340
150		275	120	112	380
200	16	547	244	106	460	1150	1170	FZS
250		794	241	124	530	1150	1170
300		1104	308	110	580	1300	1320
350		1432	306	123	660
400		1787	303	136	720
450		2198	298	150	780
500		2642	294	163	850
600		3759	431	209	1000	1800	1824
Design pressure Pd=1.0MPa (10kgf/cm²) Fatigue life [N]=200 Design temperature t=20℃
80	20	108	105	112	290	900	910	FZ
100		146	103	132	310
125		205	99	160	340
150		276	95	189	380
200	16	551	201	174	460	1150	1170	FZS
250		798	195	211	530	1150	1170
300		1109	252	180	580	1300	1320
350		1437	248	204	560
400		1793	243	227	720
450		2205	238	252	780
500		2649	233	276	850
600		3772	343	368	1000	1800	1824
Design pressure Pd=1.6MPa (16kgf/cm²) Fatigue life [N]=200 Design temperature t=20℃
80	20	108	124	155	290	900	910	FZK
100		145	123	181	310
125		204	120	215	340
150		275	117	253	380
200	16	551	211	372	460	1150	1160	FZS
250		798	205	450	530	1150	1160
300		1109	257	407	580	1300	1320
350		1437	253	461	660
400		1793	248	514	720
450		2205	243	570	780
500		2649	239	625	850
600		3772	336	679	1000	1800	1824

The recommended values of θ (θ max'')
Nominal Diameter		≤200	250	300	350	400	450	500	600	700	≥800
θ max	n group	50	45	42	40	35	32	30	28	26	23
θ max	Ω group	≤60

The main technical parameters table
Sequence Number	Nominal diameter	Compensation amount Δ(mm)	Take over the outside diameter	Flange OD	Length L (mm)	Torque M(KN.m)
Sequence Number	Nominal diameter	Compensation amount Δ(mm)	D1(mm)	D2(mm)	Length L (mm)	Torque M(KN.m)
1	50	0~1000	57	189	380	0.584
2	65	0~1000	76	208	380	0.72
3	80	0~1000	89	233	380	1.11
4	100	0~1000	108	252	380	1.29
5	125	0~1000	133	268	380	1.83
6	150	0~1200	159	303	380	2.35
7	200	0~1200	219	373	400	3.93
8	250	0~1500	273	425	420	8.11
9	300	0~1800	325	477	440	14.48
10	350	0~1800	377	526	460	18.5
11	400	0~1800	426	580	460	25.84
12	450	0~2000	480	630	460	36.21
13	500	0~2000	530	690	480	45.12
14	600	0~2000	630	790	480	63.23
15	700	0~2000	720	930	500	72.7
16	800	0~2000	820	1028	500	93.2
17	900	0~2000	920	1130	520	110.5
18	1000	0~2000	1020	1236	520	125
19	1100	0~2000	1120	1342	530	145.6
20	1200	0~2000	1220	1438	530	163.7
21	1300	0~2000	1320	1536	540	186.1
22	1400	0~2000	1420	1642	550	202.5
23	1500	0-2000	1520	1750	560	228.7
24	1800	0~2000	1910	2050	600	305.4
25	2000	0~2000	2110	2110	610	386.2