Braided flexible hose and tied expansion joints are both used to restrain pressure thrust while allowing movement in a piping system, and the two are often confused. Selecting the wrong product can result in inadequate movement capacity, unrestrained pressure thrust, or a connection that does not fit the available space envelope. This guide explains what each product is, how each restrains pressure thrust, what movement each is built to handle, and how to decide between them.
What Is a Braided Flexible Hose?
A braided flexible hose consists of a corrugated metallic hose core surrounded by one or more layers of metallic wire braid. The corrugated hose provides flexibility, allowing the assembly to bend or move laterally, while the external braid provides reinforcement and contains the pressure thrust generated by internal pressure.
What Is a Tied Expansion Joint?
A tied expansion joint is a metal bellows expansion joint fitted with tie rods that run between the assembly’s end flanges through tie-rod lugs. The bellows provide flexibility, allowing the joint to absorb lateral or angular movement, while the tie rods restrain the pressure thrust generated by internal pressure and keep that force from acting on the connected piping or equipment.
How Each Restrains Pressure Thrust
A tied expansion joint and a braided flexible hose can serve similar functions, particularly where lateral movement is required while pressure thrust must be restrained. A tied expansion joint uses tie rods connected to the assembly through tie-rod lugs. The rods restrain pressure thrust while allowing the intended lateral or angular movement. A braided flexible hose achieves the same result differently: the corrugated hose provides flexibility by bending along its length, while the external braid resists pressure thrust and limits axial movement.
When a Tied Expansion Joint Is the Better Choice
A tied expansion joint design, like PTP’s tied universal expansion joint, is generally preferred when the application requires:
- Larger, controlled lateral movement
- A short overall assembly length
- Precisely defined movement capability
- High axial or lateral structural loads
- Large pipe diameters
- Specific spring-rate requirements
- Engineered movement under thermal expansion
- Specialized liners, covers, or flow-control features
When Braided Flexible Hose Is the Better Choice
A braided flexible hose is generally preferred when the application requires:
- Installation in a space too tight for tie-rod hardware and its movement envelope
- Vibration isolation at rotating or reciprocating equipment such as pumps, compressors, or turbines
- Only a relatively small amount of lateral movement
- Tolerance for limited installation misalignment between equipment and piping
- A simpler assembly that is faster to manufacture, inspect, and replace
- A connection that is removed and replaced periodically, such as at equipment that is pulled for service
Selection Guide
| Choose Braided Flexible Hose When | Choose a Tied Expansion Joint When |
| Movement is relatively small | Larger lateral movement is required |
| Vibration isolation is important | Movement must occur within a short, defined length |
| A flexible equipment connection is needed | Movement and spring forces must be accurately controlled |
| Space or installation simplicity is important | The application involves larger piping or significant system loads |
| Pressure thrust needs to be internally restrained | Engineered accessories such as liners or covers are required |
| A simple, replaceable assembly is preferred | A specific spring rate is required |
Talk to a Piping Specialist
Not sure whether your application calls for a braided flexible hose or a tied expansion joint? Schedule time with an engineer for a review, or explore our full range of expansion joint solutions to see tied, universal, hinged, and gimbal designs in detail.
Ready to move forward? Request a quote, and our engineering team will follow up with pricing and lead time for your application.
