What Is a Flange Cover?

A flange cover is a device used to protect pipe flanges during shipping or operation. These flanges consist of a raised ring used to connect two or more pipes, making them vulnerable to impacts, leaks, and other forms of damage. Flange covers are typically made from some form of plastic, and serve as an economical and easy-to-use tool for protecting pipe flanges. These covers help to keep out dirt and moisture during shipping, and serve as a way to prevent or identify leaks once the flanges have been installed.

While flange covers come in many different sizes, some of the most common are designed to meet national or international materials standards. For example, an American National Standards Institute (ANSI) flange cover is designed to fit ANSI piping and flange sizes, while an American Society of Mechanical Engineers (ASME) flange cover meets a different set of sizing standards. Other manufacturers may use international sizing standards or those used by the military.

Different types of flange covers require their own specialized installation techniques. Covers made from soft, flexible plastic slide over the flange like a sock, and can be installed or removed by hand. Snap on models include a stiff ring that snaps into place on the back of the flange, providing a more secure fit than slip on units. Wraparound models feature a strip of material that surrounds the perimeter of the flange and is fastened in place with pins. Funnel-shaped flange cover units feature a slim base that fits inside the pipe, and a larger plate that protects the entire surface of the flange.

Flange cover materials can vary by application and environment. Most are made from plastic, including vinyl, polyethylene and polyurethane. These flange covers are both economical and easy to use. More advanced wraparound models are made from vinyl, fiberglass, or composites. Covers made from stainless steel rings are designed to withstand the most corrosive environments, which may damage plastic covers.

While the flange cover is a relatively simple device, it provides a number of advantages in terms of protecting the flange and surrounding area. When used during shipping, the flange cover keep moisture, dust, and debris out the flange and pipe. It also protects the flange from damage if it is dropped or handled roughly. When used after a flange has been installed, the flange covers protects the flange and its fasteners from corrosion, rust, and damage. Some units are even designed to change color to indicate a liquid or vapor leak at the joint between two pipes.