How does a line blind valve work?

Blind valves, also known as line blind valves, 8 blind, or blind flanges are safety components that completely restrict flow through a pipe. They can be as simple as a rotating “8” shape, where one loop is completely solid (shown in Figure 1) and the other is a hollow disc that allows for flow through the valve.

What is line blind?

Line blinds are safety devices designed for positive shut-off of piping, equipment or storage tanks where positive shut-off is defined as a device in a closed, drop-tight, verifiable, and maintainable position.

What is a blind flange valve?

A blind flange is a solid flange as shown below. The purpose of these is to block off a section of pipe or a nozzle on a vessel that is not used. (A nozzle is typically a pipe coming out of a vessel and is usually flanged so it can be connected to valves or piping).

What is a Hammer blind valve?

Valves, Flow Meters & Wing Unions Hamer® Line Blind Valves ensures positive and visible knowledge that a pipeline is blinded with a rotating spectacle plate that shows flow or no-flow. It incorporates a tough, simple design that provides long lasting service life with minimal maintenance requirements.

When do you use a line blind valve?

Line Blind Valves are often used along with block and bleed valves to provide positive isolation for maintenance After the block and bleed valve is closed and equipment is depressurized and drained, the Line blind can be operated into a close position to provide additional isolation from process fluids entering the maintenance area.

When do you need to use line blinding?

Line blinding has been used to pipelines in various industries wherever either positive shutoff is most concerned or full flow should be achieved without pressure drop. The usual practice for line blinding by using typical materials such as spectacle blinds, spool piece, blind flange valves etc.

What does the spectacle plate on a Hamer line blind do?

The spectacle plate system on all Hamer® Line Blind Valves provides a positive, visual indication of the valve’s open or closed status.

Can a line blind be diverted to other equipment?

The flow can be diverted to other items of equipment but not just bypassed around the blank as this would compromise the safety function of the spectacle blind. The flow has to be valved off and pressure relieved prior operating the line blind.