Pipeline Mechanical Connector/Flange

A pipe flange is a disc, collar or ring that attaches to pipe with the purpose of providing increased support for strength, blocking off a pipeline or implementing the attachment of more items. They are usually welded or screwed to the pipe end and are connected with bolts. A gasket is inserted between the two mating flanges to provide a tighter seal. These flanges are either custom with dimensions provided by the customer or they are manufactured according to published specifications. Several organizations and associations have published specifications that provide dimensional information as well as pressure specifications at different temperatures. Our company manufactures custom designs and stocks six basic types of these products. Although, these are the six most common types, we are a custom manufacturer as well and are able to create just about any type of flange necessary for your requirements. Please click on one of the following pictures for a more detailed description of the item you are interested in. Each page also has a video that provides a better understanding of the installation process.

Types of flange


Slip-on pipe flanges actually slide over the pipe. They are typically machined with an inside diameter slightly larger than the outside diameter of the pipe. This allows the flange to slide over the pipe but to still have a somewhat snug fit. Slip-ons are secured to the pipe with a fillet weld at the top and the bottom of the flange. These are further catagorized as a ring or a hub. Rings and hubs are both considered slip on flanges because they both fit over the pipe.

Slip-on flange
Source: http://www.coastalflange.com/images/slip-on-pipe-flanges-thumb.jpg
Weld neck

Weld neck pipe flanges are installed by welding the pipe to the neck of the flange. This allows for the transfer of stress from the flange to the pipe itself. This also reduces high stress concentration at the base of the hub. Weld necks are often used for high pressure applications. The inside diameter of this attachment is machined to match the inside diameter of the pipe.

Weld neck flange
Source: http://www.coastalflange.com/images/weld-neck-pipe-flanges-thumb.jpg
Blind pipe flanges are used to seal the end of a piping system or pressure vessel openings to prevent flow. They are commonly used for pressure testing the flow of liquid or gas through a pipe or vessel. They also allow easy access to the pipe in the event that work must be done inside the line. Blind pipe flanges are often used for high pressure applications.

Blind flange
Source: http://www.coastalflange.com/images/blind-pipe-flanges-thumb.jpg
Lap joint

Lap joint pipe flanges fit over the pipe and are most commonly used with Stub End Fittings. A pipe is typically welded to the Stub End and the Lap Joint is free to rotate around the stub end. The benefit of this is that there will not be any issues with bolt hole alignment. These are often used for applications that require frequent dismantling.

Lap joint flange
Source: http://www.coastalflange.com/images/lap-joint-pipe-flanges-thumb.jpg

Threaded pipe flanges are similar to slip-ons except the bore of threaded pipe flange has tapered threads. They are used with pipes that have external threads. The benefit of these is that it can be attached without welding. Threaded pipe flanges are often used for small diameter, high pressure requirements.

Threaded flange
Source: http://www.coastalflange.com/images/threaded-pipe-flanges-thumb.jpg
Socket-weld pipe flanges are typically used on smaller sizes of high pressure pipes. These flanges are attached by inserting the pipe into the socket end and applying fillet weld around the top. This allows for a smooth bore and better flow of the fluid or gas inside of the pipe.

Socket-weld flange
Source: http://www.coastalflange.com/images/socket-weld-pipe-flanges-thumb.jpg

Hydraulic Smart Flange (HSF)
For deepwater pipeline and riser repairs, Oceaneering PCRS offers a hydraulically- set mechanical connector based on the proven technology of the Smart Flange Plus Connector. The connector is designed to provide a structural connection point subsea. When actuated, the Hydraulic Smart Flange (HSF) Connector will structurally attach to and seal against the pipe. It’s capable of withstanding full pipeline axial, bending, and torsional loads while maintaining full line pressure integrity.

Hydraulic smart flange
Source: http://www.oceaneering.com/wp-content/uploads/2010/01/subprod-prs-hsf.jpg
The HSF may be provisioned with a Grayloc® male hub, a flange, or may be connected with another HSF in a double arrangement, making it a double grip and seal type connector. The ROV uses a single hot stab to pressurize the port in the connector in order to set the gripping and sealing mechanisms on the pipe.

The HSF has dual setting pistons. During the initial setting of the connector, the seal piston is driven axially to set the main and test seals around the pipe. The pressure is then increased to drive the slip piston axially in the opposite direction from the seal piston to set the gripping mechanism on the pipe. Both pistons are locked into final position by a series of spring-energized ratcheting locking mechanisms positioned radially inside the connector housing. These locking devices ensure a positive lock preventing any possible back driving. An annulus test port feature allows the sealing integrity to be confirmed by pressurizing the annulus between the main and test seals.

Hydraulic Smart Flange (HSF) Connectors can be designed in sizes and pressure ratings to meet any customer requirements. The connectors are available in configurations with other connectors and fittings.



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