Metal Expansion Joints & Compensators
JDZ Internal Pressure Axial Metal Expansion Joint
An internal-pressure metal bellows expansion joint designed to absorb axial thermal expansion and contraction in straight piping systems while reducing thermal stress transmitted through the pipeline.
Also commonly described as an axial bellows expansion joint, axial compensator, bellows compensator or corrugated compensator. JDZ is the Mingchao model designation for the internal-pressure axial configuration.
- Model
- JDZ
- Product Type
- Internal Pressure Axial Metal Expansion Joint
- Primary Movement
- Axial
- Core Standard
- GB/T 12777-2008
- Design Pressure
- 0.25–2.5 MPa
- Design Temperature
- -20°C to +400°C
- Published Technical Table
- DN32–DN350
- Large / Custom Sizes
- Up to DN7000 on request
- Axial Compensation
- Varies by DN, wave number and pressure level
- Connection
- Flange connection; grooved option only for confirmed configurations
Stock / Fast ShipmentMany common sizes and configurations are kept in stock for faster shipment.
CustomizationWave number, length and materials can be customized according to confirmed operating conditions and project requirements.
Project Configuration
Mingchao can customize the product configuration based on the technical information, operating conditions and dimensional data you provide. Final configuration can be reviewed and manufactured to the approved project drawing.
JDZ Internal Pressure Axial Metal Expansion Joint Overview
The JDZ is an internal-pressure axial metal expansion joint designed to absorb longitudinal thermal expansion and contraction in piping systems. As pipeline temperature changes, the corrugated bellows flexes in the axial direction, helping reduce thermal stress transferred through straight piping runs and connected components.
The JDZ is intended primarily for axial movement compensation. Mingchao technical data also identifies limited lateral and angular movement capability; these secondary movements should only be considered where they are confirmed by the selected configuration and actual operating conditions.
Manufactured to GB/T 12777-2008, the JDZ series covers design pressures from 0.25 MPa to 2.5 MPa and design temperatures from -20°C to +400°C. Published technical data provides detailed axial compensation, stiffness and dimensional information by nominal diameter, wave number and pressure level. Larger and project-specific configurations are available according to confirmed operating conditions and drawings.
Technical Specifications & Axial Compensation
Axial compensation and stiffness vary according to nominal diameter, bellows wave number and pressure level. In the Mingchao technical data, each pressure-level value combines axial compensation in millimetres with stiffness in N/mm. Pressure-column format: Axial Compensation (mm) / Stiffness (N/mm).
| DN | Wave Number | 0.25 MPa | 0.6 MPa | 1.0 MPa | 1.6 MPa | 2.5 MPa | Effective Area of Bellows (cm²) | Max Outside Diameter (mm) | Length — Flange (mm) | Length — Pipe-End / Take-Over (mm) |
|---|---|---|---|---|---|---|---|---|---|---|
| 32 | 8 | 25/21 | 22/26 | 20/26 | 18/63 | — | 16 | 225 | 160/250 | 264/280 |
| 32 | 16 | 50/11 | 46/14 | 41/14 | 36/32 | — | 16 | 225 | 224/291 | 316/321 |
| 40 | 8 | 25/28 | 22/44 | 20/44 | 18/89 | 15/98 | 23 | 244 | 164/259 | 269/289 |
| 40 | 16 | 50/14 | 46/22 | 41/22 | 36/45 | 31/47 | 23 | 244 | 230/304 | 319/334 |
| 50 | 8 | 25/30 | 22/51 | 20/70 | 18/70 | 15/106 | 37 | 259 | 172/276 | 282/306 |
| 50 | 16 | 50/16 | 46/26 | 41/35 | 36/35 | 31/55 | 37 | 259 | 240/342 | 347/372 |
| 65 | 8 | 33/28 | 30/35 | 26/44 | 22/55 | 15/138 | 55 | 270 | 215/294 | 300/322 |
| 65 | 12 | 42/16 | 38/22 | 38/32 | 34/40 | 31/70 | 55 | 270 | 260/334 | 340/362 |
| 80 | 8 | 40/20 | 36/26 | 34/33 | 28/41 | 19/68 | 81 | 284 | 240/338 | 344/366 |
| 80 | 10 | 53/14 | 49/17 | 49/21 | 43/26 | 29/50 | 81 | 284 | 270/368 | 374/390 |
| 100 | 6 | 45/47 | 45/60 | 40/75 | 35/93 | 25/54 | 121 | 304 | 235/317 | 323/345 |
| 100 | 10 | 76/26 | 74/32 | 64/40 | 57/50 | 38/33 | 121 | 304 | 305/381 | 387/409 |
| 125 | 5 | 48/38 | 42/47 | 38/59 | 34/74 | 29/117 | 180 | 334 | 282/314 | 316/342 |
| 125 | 9 | 85/23 | 77/29 | 66/36 | 58/45 | 49/63 | 180 | 334 | 382/386 | 388/414 |
| 150 | 5 | 49/42 | 44/50 | 40/62 | 34/78 | 29/92 | 257 | 364 | 282/339 | 338/367 |
| 150 | 8 | 79/34 | 71/43 | 64/51 | 54/59 | 50/56 | 257 | 364 | 356/399 | 402/427 |
| 200 | 4 | 52/49 | 46/55 | 42/68 | 38/78 | 29/97 | 479 | 442 | 280/348 | 348/372 |
| 200 | 6 | 73/31 | 65/44 | 59/52 | 53/58 | 46/65 | 479 | 442 | 340/402 | 402/426 |
| 250 | 4 | 72/30 | 65/34 | 59/42 | 52/45 | 34/111 | 769 | 507 | 315/379 | 415/379 |
| 250 | 6 | 108/16 | 97/21 | 87/35 | 79/39 | 48/78 | 769 | 507 | 393/459 | 493/399 |
| 300 | 4 | 72/51 | 65/55 | 59/59 | 52/65 | 47/55 | 1105 | 562 | 366/427 | 466/467 |
| 300 | 6 | 108/32 | 97/35 | 87/37 | 79/41 | 71/47 | 1105 | 562 | 464/525 | 564/565 |
| 350 | 4 | 72/58 | 65/62 | 59/67 | 52/74 | 47/71 | 1307 | 622 | 397/452 | 497/492 |
LARGER SIZES AVAILABLE — Sizes above the published technical table can be manufactured up to DN7000 on request. Bellows wave number, axial compensation, stiffness, overall length and connection dimensions are confirmed according to the required pressure, temperature, operating conditions and approved drawings. Axial compensation values are reference values. Final selection must be confirmed according to the actual operating conditions.
Pressure, Temperature & Connection Configuration
The JDZ series is available across multiple design-pressure levels from 0.25 MPa to 2.5 MPa, with a stated design-temperature range of -20°C to +400°C. The required pressure level must be selected together with nominal diameter, axial movement, overall length and actual operating conditions.
The main JDZ flange connection dimensions should be confirmed against the connected pipeline and approved project drawing. Mingchao source material also shows a grooved connection option; it is secondary to the main flange configuration and must be confirmed for the selected JDZ arrangement. Project-specific connection dimensions and configurations can be reviewed according to confirmed drawings and operating requirements.
Core standard: GB/T 12777-2008.
Bellows Construction & Custom Options
The corrugated metal bellows is the flexible working element of the JDZ axial expansion joint. Mingchao drawings show the bellows assembly together with end-pipe and connection components used to integrate the joint into the piping system.
Wave number, overall length and material configuration can be selected according to confirmed pressure, temperature, medium, required axial compensation and project requirements.
| Item | Configuration |
|---|---|
| Model | JDZ |
| Bellows | Corrugated metal bellows |
| End Pipe | End-pipe component shown in the Mingchao JDZ assembly drawing |
| Connection Components | Flange components shown for the main configuration; a grooved option is also shown in source drawings |
| Tie Rod | Present in the Mingchao source drawing |
| Wave Number | Multiple configurations according to technical data |
| Special Length | Available according to requirement |
Applications for Steam, Hot Water, HVAC & Industrial Piping
Steam, Hot Water & Thermal Oil Pipelines
Absorbs axial thermal expansion and contraction in pipelines exposed to significant temperature changes.
Power, Chemical & Petrochemical Piping
Provides axial movement compensation in industrial process piping operating under confirmed pressure and temperature conditions.
HVAC & District Heating
Used in heating and thermal-distribution piping where longitudinal pipe expansion must be accommodated.
Municipal Heating & Utility Piping
Suitable for municipal and utility piping systems requiring controlled axial thermal movement compensation.
Pump & Valve Connections
Can be used in piping sections around pumps and valves where thermal movement and installation conditions require a metal bellows connection.
General Process Piping
Provides compact axial compensation for straight industrial piping runs and process systems.
How to Select a JDZ Axial Expansion Joint
Correct JDZ selection depends on the actual thermal movement, operating conditions and connection requirements of the piping system. Provide the main project data below so that the required bellows configuration, wave number, pressure level and dimensions can be confirmed.
- Nominal diameter / DN
- Design or working pressure
- Design or working temperature
- Medium / fluid
- Required axial compensation
- Required installation / overall length
- Connection type and mating dimensions
- Material requirement, if specified
- Quantity
- Project or piping drawing, if available
Final configuration is confirmed against the supplied operating data and drawings.
Internal-Pressure vs. External-Pressure Axial Expansion Joints
| Product Type | Configuration |
|---|---|
| JDZ Internal Pressure Axial Metal Expansion Joint | Primary role: axial thermal movement compensation using the internal-pressure JDZ configuration. Primary search intent: axial metal expansion joint / internal pressure axial expansion joint. |
| JZW Axial External-Pressure Corrugated Expansion Joint | Primary role: external-pressure axial configuration. Primary search intent: external pressure axial expansion joint. |
| Grooved-End Bellows Expansion Joint | Connection-focused bellows product using grooved ends. Primary search intent: grooved bellows expansion joint. |
Installation & Piping Design Considerations
Confirm the selected JDZ configuration against the approved piping-system design before installation.
Axial Compensation
Confirm the required axial compensation against the actual operating conditions.
Operating Data
Verify selected pressure level, temperature, medium, overall length and connection dimensions before installation.
Approved Drawings
Follow the approved product and project drawings for the final installation configuration.
Movement Direction
JDZ is selected primarily for axial movement; unintended movement outside the confirmed design conditions should not be assumed to be acceptable.
Piping System
Final piping support, anchor and guide arrangement should follow the approved piping-system design.
JDZ Product Photos & Technical Views
Technical Documents / Reference Information
- GB/T 12777-2008
- JDZ Technical Dimension & Axial Compensation Data
- Project-specific technical drawing available after configuration review
- Large-size / custom dimensional data confirmed according to project requirements