Loose Flange manufacture & supply in China

Loose flange is a type of flange with a unique connection method. Because it consists of two parts, a flange ring and a short pipe. The installation method is to insert the flange ring into the short pipe and weld the stud end to the pipeline. The flange ring is not welded, only needs to be fixed with bolts and nuts to the flange that needs to be connected. The advantage of this is that if the flange hole at the connection end does not correspond to it, only the flange ring needs to be rotated. No need to rotate the pipeline anymore.

The production standards for loose flange include ASME, DIN, EN, etc. Among them, DIN is mostly a European standard. ASME is commonly used in American standards and can also be used in internationally recognized standards. Different standards specify different sizes, specifications, and pressures.

Therefore, if purchasing loose flanges, detailed specifications must be provided. More detailed standards need to be established for short pipes.

The production standards for loose flange mainly include ASME, DIN, EN, etc. Both the flange ring and short pipe have clear and detailed data standards.

ASME B16.5 is one of the standards for flanges in the overlap flange of ASME B16.5. The flanges produced are mainly used together with overlapped short pipes. The usage method is to weld the short pipe to the pipeline and connect the flange ring to the flange at the other end. This type of flange can align the flange holes without welding, as the flange ring can be moved.

When quoting, we will provide an accurate quote based on your specific data, such as size, pressure, raw materials, aperture, number of holes, etc.

EN 1092-1 Loose Plate Flange is a type of flange standard that belongs to the European standards. There are two types of Loose Plate Flanges: butt welded loose flange and flat welded ring loose flange.

The nominal size of the flange specified in this standard is represented by DN, which ranges from DN10 to DN600. The pressure level is represented by PN, and commonly used levels include PN2.5, PN6, PN10, PN16, PN25, and PN40. It cannot be interchanged with ASME B16.5 due to different scope standards.

DIN 2642 PN10 Loose Flange is an older German standard. It is now rarely used. Most people now use EN 1092-1 Type 02.

The DIN 2642 standard also provides detailed specifications for various data. Such as flange outer diameter, thickness, size, pressure rating, etc.

The specifications and dimensions of loose flanges vary according to different standards. If detailed drawings are provided, production can also be carried out. If it is only DN100 PN10, it cannot be produced.

Here are some specifications and standards for loose flanges:

The loose flange of ASME B16.5 standard has clear flange grades, flange outer diameter, thickness, number of holes, aperture, etc.

DIN 2642 PN10 loose flange refers to the DIN2642 standard with a pressure rating of 10, but there is no standard size, flange thickness, number of holes, etc. Therefore, before providing a specific quotation for production, it is necessary to communicate with the customer to determine the specific dimensions.

The flange ring of the loose flange can rotate on the short pipe, so in the absence of alignment, simply rotate the flange ring to achieve alignment. This type of flange is very suitable for connecting large-diameter pipelines.

Post maintenance is also very convenient, just remove the bolts and nuts used for flange connection.

Since the loose flange is composed of two parts, if the transported medium contains corrosiveness, only corrosion-resistant raw materials need to be used for the short pipe. The corrosion resistance of the raw material of the flange ring can be lower than that of the short pipe because it does not require contact with the transport material. This can reduce costs.

If it is a large-diameter pipeline or a place with small installation space, it is more suitable for aligning flange holes. No overall rotation of the pipeline is required.

Do not order a loose flange using only DN/NPS and pressure rating. Before quotation or replacement, confirm the standard, loose-flange type, stub-end or collar type, pipe outside diameter, relevant wall thickness, flange bore, inner radius or chamfer, flange thickness, bolt circle, bolt-hole quantity and diameter, loose-ring material, and companion-component material.

A common replacement risk occurs when a drawing or existing installation uses DIN 2642 while a new quotation refers to EN 1092-1 Type 02. Even when both descriptions show the same DN and PN, the drilling, thickness, bore, and collar geometry should be compared before the order is released.

The material selection and matching of loose flange refers to the material of the flange ring and short pipe or collar. Because these components have different functions, different materials can be used in some selected environments.

In some conventional industrial systems, such as those without corrosion and with medium to low pressure levels. If the project allows, mixed materials can be used to make loose flanges. Lower grade carbon steel can be chosen for the gasket ring.

In some designated projects or projects that involve corrosion or require rust prevention, the entire flange must be made of stainless steel material.

In some designated projects, there are special requirements for pipeline grades, design temperatures, mechanical requirements, etc. We can produce loose flanges made of specified alloy materials according to customer requirements.

In some projects with low corrosion resistance requirements, short pipes can be made of stainless steel material, while flange rings can be made of high-performance carbon steel or other alloy steel. Because there is no corrosive environment outside, and the flange ring does not come into contact with the internal transport material.

The structure of loose flange and slip on flange is different. Loose flange is composed of two parts, while slip on flange is a whole. 

Loose flanges are also widely used and can be selected in the following situations:

Of course, the above projects are for reference only, and specific projects need to be determined through communication with engineers. Because different environments, applications, or transportation materials have different requirements for their connection.

When there is a requirement for corrosion resistance in pipeline systems, it is possible to choose to use corrosion-resistant materials for short pipes that come into direct contact with transportation. And the material of the flange ring can be selected separately. This can ensure that it has good corrosion resistance and that its cost is not too high.

Due to the corrosiveness of seawater and its tendency to rust pipes. Therefore, corrosion resistance can be selected for short pipes, while flange rings have lower requirements for corrosion resistance.

Due to the limited operating space of the vessel, loose flanges were chosen. It can effectively avoid the phenomenon of misaligned flange holes.

In equipment that requires regular inspection and cleaning, choosing loose flanges is more conducive to disassembly.

When connecting pumps, storage tanks, heat exchangers, etc., it is more convenient to use loose flanges for flange hole alignment and connection because it is not possible to produce positioning pipelines.

Our company conducts testing from the procurement of source materials to the completion of product production. Ensure traceability is possible.

The production of flanges strictly follows production standards and there will be no tolerances. And our company has a high forging process. We have the latest machining machines and all employees have 5 years of frontline production experience.

Non destructive testing will be conducted during the flange blank stage, and a final inspection will also be conducted on the product before shipment. To determine the accuracy of the product.

The size inspection of flanges includes whether they are marked, and whether the outer diameter, thickness, aperture, number of holes, and other dimensions of the flange are consistent with the standard.

All the above tests will be saved in the form of documents. If third-party testing is required, we will also ask the third party to provide a paper test report. Send it together to the customer.

The standard testing of flanges, loose flange nominal can meet the rated values of DN/NPS, etc. But the data of its collar or short tube end also needs to be tested.

Metleader can supply steel pipes, fittings, flanges, valves, and some supporting products such as bolts, nuts, and gaskets. If you need one-stop procurement of these products, please feel free to choose us.

Our company’s products are strictly produced according to customer requirements and meet the standards required by customers, such as ASME, DIN, JIS.  

We can provide short pipes, collars, or related bolts, nuts, and washers required for loose flanges as needed by customers.

Our products undergo strict testing from the entry of raw materials to the exit of the factory, such as raw material testing, production testing, non-destructive testing, and conventional dimensional testing. And these tests have documentation for customers to easily view.

We can assist overseas buyers with packaging and shipping support. And provide the necessary information for overseas needs.

Prepare an accurate quotation and avoid a mismatch between the loose ring and its companion component, please provide as much of the following information as possible:

If you have a project drawing, standard data sheet, or measurements from an existing connection, send them with the RFQ. We can identify missing parameters before quotation.

Not exactly the same, lap joint flange is a type of loose flange. The size and matching parts of the European standard plate loose flange and the American standard LJ loose flange are different, and the two cannot be interchanged. There are different production standards for each of them.

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Because flange rings are used in conjunction with short pipe ends, collars, or overlapping pipes. They together form the loose flange.

Loose flanges have separate short pipes or collars that can be rotated to fit the flange holes. Slip on flange is an integral flange that is directly welded to the pipeline.

It can be used in some applications. Because the flange ring does not come into contact with the transported material, it is only in the external environment. So if the project allows, it can be used in this way.

Cannot be completely interchangeable, can only be temporarily replaced under limited conditions. Because the sizes of the two standards are not exactly the same. Because there are differences in their dimensions.

It is necessary to check the outer diameter, thickness, number of holes, aperture, and pressure rating of the flange, as well as the size of the short pipe end.