J-VALVES Selection of Gate Valve Connection Methods

I. Detailed Analysis

1.Flange Connection
· Advantages:

Standardized interfaces with strong adaptability, supporting multiple flange types such as RF and RTJ.

Detachable design, facilitating valve replacement or system expansion.
· Disadvantages:

Bolts are prone to loosening and leakage at high temperatures (>350°C).

It occupies a large space and is not suitable for compact installation scenarios.
· Applicable Scenarios:

Medium and high-pressure systems such as petrochemical and LNG stor

2. Threaded Connection
· Advantages:

Quick installation without the need for professional tools, suitable for pipelines below DN50.

Low cost and widely used in low-pressure water heating systems.
· Disadvantages:

Threads are easily loosened due to vibration and require regular inspection of the sealing performance.

Not suitable for high-temperature, high-pressure or corrosive media.
Applicable Scenarios: Low-pressure environments such as household water supply and pressure gauge interfaces.

3. Welded Connection
· Advantages:

No leakage risk, suitable for extreme temperatures/pressures.

Compact structure without the weight of additional connectors.
· Disadvantages:

Requires professional welders, and disassembly requires cutting of pipelines.

Weld seams may fail due to medium corrosion or vibration fatigue.
Applicable Scenarios: 

Long-term high-load systems such as nuclear power plants and ethylene cracking units.

II. Selection Suggestions

1. Give priority to flange connection: For medium and high-pressure pipelines that require frequent maintenance or system expansion (such as refineries).

2. Give priority to threaded connection: For low-pressure, small-diameter and vibration-free scenarios (such as household water supply).

3. Give priority to welded connection: For harsh working conditions with ultra-high temperature/high pressure and requirements for permanent sealing (such as nuclear reactor cooling systems).

III. Precautions

1. Flange Connection: When choosing RF or RTJ flange types, it is necessary to match the pipeline pressure rating.

2. Threaded Connection: Be sure to use NPT standard threads and wrap sealing tape.·

3. Welded Connection: Weld seam inspection should be carried out in accordance with the ASME B31.3 specification.