Flange Sealing and Leak Repair Methods
Flange Sealing
The effectiveness of a flange seal depends on several factors. These include the bolt preload, the type of sealing surface, the performance of the gasket, the stiffness of the flange, and the operating conditions. [Flange seal manufacturer, flange seal supplier, flange seal provider]
ANSI flanges, designed by the American National Standards Institute, have long been used in the oil and gas industry for reliable sealing. However, as industry demands evolve, the limitations of ANSI flanges are becoming more apparent. In the 21st century, cost efficiency, environmental sustainability, and health and safety have become critical concerns for operators and contractors. As a result, new sealing technologies are being explored. The basic principle of ANSI flanges is simple: bolts press the two flange faces against the gasket to create a seal. But this method causes wear on the gasket over time. To maintain the seal, large amounts of bolt force are required, which leads to larger bolts, bigger nuts, and thicker flanges. This increases the overall size and weight of the system, which is a major issue in offshore environments where weight is always a concern. Additionally, ANSI flanges are inherently inefficient, with about 50% of the bolt load used to compress the gasket, while only 50% is used to hold the pressure.
A major drawback of ANSI flanges is their inability to guarantee a leak-free connection. The design is dynamic, and cyclic loads such as thermal expansion or mechanical vibrations can cause movement between flange faces, leading to loss of integrity and eventual leakage.
Vector has developed a new compact flange that addresses these issues. This flange offers all the advantages of traditional designs but with significant improvements. It saves space, reduces weight, and ensures a leak-proof joint. The smaller size comes from a reduced sealing diameter and the use of a sealing ring instead of a traditional gasket. This allows for lower pressure requirements, reducing the size and number of bolts needed. The result is a lightweight, compact solution—up to 70-80% lighter than standard ANSI flanges.
Flange Leak Sealing Treatment Method [Flange seal manufacturer, flange seal supplier, flange seal provider]
I. Location and Condition of the Leak
There is a leak at the flange bolts on both sides of a DN150 valve body. Due to the extremely small gap between the flanges, it's not possible to inject sealant through the gap to stop the leak. The leaking medium is steam, with temperatures ranging from 400 to 500°C and system pressure at 4 MPa.
II. Sealing Construction Method
Based on an on-site inspection, a fixed clamp method was used to contain the leak point and form a sealed cavity. Sealant was then injected to eliminate the leakage.
1. Fixture Design
(1) Determination of the fixture structure
- Contain the leak point and establish a sealed cavity between the valve body flange and the pipe flange short flange. To prevent potential leaks due to pressure, an annular cavity is filled at the outer edge of the clamp and the valve body flange.
- During injection into different diameter flanges, the clamp may shift toward the smaller flange side. To prevent this, a tooth-shaped clamping mechanism is used.
2. Selection of Sealant and Estimation of Usage [Flange gasket manufacturer, flange seal manufacturer, flange seal provider]
(1) Sealant Selection
TXY-18#A sealant was chosen based on the temperature and leakage characteristics. It offers excellent heat resistance, chemical resistance, and ease of application. It creates a uniform, dense seal that remains stable over time.
(2) Estimation of Sealant Quantity
Each side requires approximately 4.5 kg of sealant.
3. Construction Process
(1) Installation of the Clamp
Due to the toothed contact, the inner diameter of the teeth is small. When installing, the outer ring of the clamp must be deformed to allow proper clamping.
(2) After completing the injection, the clamp, valve body, and flange annular cavity are filled. The intermediate cavity is also injected, with balanced pressure applied to avoid stress relaxation.
(3) Once the sealant is cured, the effect is observed, and any local refilling is done to prevent stress relaxation. Finally, the injection hole is closed. (Source: Shengwei Seal)
Expanded PTFE Gasket
Product Manual:
1. Made from 100% expanded PTFE, highly resistant to most chemicals;
2. Soft, flexible, and tightly bonded to flanges;
3. Excellent resistance to cold flow and creep;
4. Suitable for alternating temperature and pressure environments.
Description: [Flange seal manufacturer, flange seal supplier, flange seal provider]
The expanded PTFE gasket is made from expanded PTFE sheets. It retains the properties of the original material and performs exceptionally well in areas with fluctuating temperature and pressure. It prevents creep and cold flow. The sheet can be tightly bonded to the flange surface, providing excellent sealing performance.
Outstanding Performance:
> Easy to install and remove
> Can replace asbestos gaskets and serve as a non-metallic alternative
> Can be enhanced with additives like glass fiber or silica for better performance
> Can be manufactured in any shape, with a simple process
Technical Data:
Operating Temperature: -286 ~ 320°C, Pressure: 19.6MPa.
[Flange seal manufacturer, flange seal supplier, flange seal provider]
Mechanical pumps may be submerged in the fluid they are pumping or be placed external to the fluid.
Pumps can be classified by their method of displacement into positive displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps and valveless pumps. There are two basic types of pumps: positive displacement and centrifugal. Although axial-flow pumps are frequently classified as a separate type, they have essentially the same operating principles as centrifugal pumps.
QFAP has specialize in producing pump housings more than 5years.
Materials: Ductile iron, Grey iron, Aluminum
Surface treatment: Painting, Powder coating, only oiled
Main of our customers is from German, USA, and CAN.
With the long terms of experience in the pump industry, we could supply the pump housings or help to design the housings according to your requirements.
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