
Rubber Expansion Joints
JGD-B Threaded Union Rubber Expansion Joint
The JGD-B Threaded Union Rubber Expansion Joint is a compact twin-sphere flexible connector for small-diameter piping where a threaded union connection is preferred to conventional flanges. Mingchao’s catalog covers DN15–DN80 with documented movement and operating-condition data, while thread form, union material, length and elastomer can be reviewed for project-specific manufacture.
THREADED UNION · SMALL-DIAMETER FLEXIBLE CONNECTION · CUSTOM THREAD OPTIONS
- Model
- JGD-B
- Catalog Range
- DN15–DN80
- Selection
- Pressure · Temperature · Medium · Movement
- Customization
- Drawing-Based
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.
JGD-B Threaded Union Rubber Expansion Joint — Overview
The JGD-B Threaded Union Rubber Expansion Joint is a compact twin-sphere flexible connector for small-diameter piping where a threaded union connection is preferred to conventional flanges. Mingchao’s catalog covers DN15–DN80 with documented movement and operating-condition data, while thread form, union material, length and elastomer can be reviewed for project-specific manufacture.
The catalog values are source references. Final suitability and operating limits require the selected material, dimensions, connection and project conditions to be confirmed.
Why Threaded Union Connections for Small-Diameter Piping
This connection geometry combines flexible isolation with the product-specific interface shown in the catalog. Selection must consider the complete piping arrangement and approved drawing.
Twin-Sphere Rubber Body & Construction
Catalog references: working pressure 1.6 MPa, burst pressure 4.8 MPa, vacuum 53.3 kPa / 400 mmHg and deflection 45°. Catalog applicable temperature is -15°C to 115°C; special -30°C to 250°C configurations require material and factory confirmation. Materials: NR / NBR / EPDM rubber, Nylon Cord Fabric, Steel Wire reinforcing ring and Forged / Cast Iron threaded union.

Unified DN15–DN80 Specifications
Unified engineering fields: DN; NPS; Face-to-Face; Movement; Thread Form; BSP / BSPT / NPT / Project Thread; Male/Female/Union Interface; Thread Size; Thread Engagement; Union Material; Rubber; Reinforcement; Pressure; Burst; Vacuum; Temperature; Medium; Weight; Drawing; Custom Thread; Custom Length. Catalog numeric fields are exact; other requirements are project-specific or factory-confirmation fields.
| DN | NPS | Face-to-Face L (mm) | Extension (mm) | Compression (mm) | Lateral (mm) | Angular (deg) |
|---|---|---|---|---|---|---|
| 15 | 0.5 | 203 | 5–6 | 22 | 22 | 45 |
| 20 | 0.75 | 203 | 5–6 | 22 | 22 | 45 |
| 25 | 1 | 203 | 5–6 | 22 | 22 | 45 |
| 32 | 1.25 | 203 | 5–6 | 22 | 22 | 45 |
| 40 | 1.5 | 203 | 5–6 | 22 | 22 | 45 |
| 50 | 2 | 203 | 5–6 | 22 | 22 | 45 |
| 65 | 2.5 | 240 / 265 | 8–10 | 24 | 24 | 45 |
| 80 | 3 | 240 / 285 | 8–10 | 24 | 24 | 45 |
Catalog movement values are individual references; combined movement requires engineering confirmation.
BSP, BSPT, NPT & Project Thread Requirements
Connection geometry and interface requirements must be stated on the customer or project drawing. Do not assume an unspecified thread, flange or angle.
Axial, Lateral & Angular Movement
Catalog movement values are individual references and must not be combined simultaneously without engineering confirmation.
Pressure, Burst, Vacuum & Temperature
Catalog references: working pressure 1.6 MPa, burst pressure 4.8 MPa, vacuum 53.3 kPa / 400 mmHg and deflection 45°. Catalog applicable temperature is -15°C to 115°C; special -30°C to 250°C configurations require material and factory confirmation. Materials: NR / NBR / EPDM rubber, Nylon Cord Fabric, Steel Wire reinforcing ring and Forged / Cast Iron threaded union.
Union Material & Rubber Selection
Material selection depends on medium, concentration, temperature, pressure and environment. Catalog materials are references, not universal compatibility guarantees.

Custom Thread, Length & Material Configuration
Drawing-based custom geometry is available subject to engineering and manufacturability review. Custom geometry does not imply unlimited pressure, temperature or movement.
HVAC, Pumps & Building-Service Applications
Typical applications require confirmation of pressure, temperature, medium, movement, supports and connection details.
Installation, Alignment & No Torsional Preload
Internal pressure creates thrust. Rubber joints do not replace anchors, guides or independent pipe/equipment supports. Installation must avoid forced alignment and torsional preload.

Project RFQ
Send DN/NPS, connection standard, pressure, temperature, medium, movement, dimensions, quantity and approved drawing for project-specific quotation.
