ASME B16.48 Spectacle Blind

ASME B16.48 is a B16 standard for valves, flanges, fittings, and gaskets.The blind works as isolation and cut-off as the head, cap and welding plug. Because of its good sealing performance, it is generally used as a reliable means of isolation for systems requiring complete isolation.

         Spectacle Blind is a pipe fitting used to isolate or connect piping systems. The spectacle blind has a structure of half blind plate and half flange. It is often used for pipeline flanges requiring process change to facilitate pipeline maintenance. Usually use the space occupied by one end of flange to keep the pipeline unblocked. If necessary, replace it with blind plate of the same thickness at the other end to cut off the pipeline. Avoid forced expansion of pipeline caused by temporary replacement of other blind plates and affecting the whole system. Commonly used for pipe flanges requiring process change, mainly made of carbon steel, stainless steel, and alloys, which can be selected according to pipe pressure level and pipe media.

Structure of ASME B16.48 Spectacle Blind

         Spectacle blind is usually isolated from other facilities or installations in piping systems. Typically, the spectacle blind is located in the open position so that the fluid passes through the pipe. When spectacle blind is in the closed position, the pipe is closed and the fluid is blocked.There is a drill hole in the connecting web of spectacle blind. Loosen and disassemble some bolts. The spectacle blind can rotate between the flanges. After replacing gaskets, the bolts can be reassembled and tightened.

• 1-Baffler

• 2-Sealing structure

• 3-Reinforcing structure

• 4-First connection station

• 5-Connection structure

• 6-Second connection station

• 7-Flow plate

Setting Principles

• If discharge of medium and high pressure equipment and pipelines is connected to open or close discharge and manual discharge is carried out, spectacle blind shall be set behind the shut-off valve.

• The spectacle blind plate shall be set at the shutoff valve at the interface reserved for the later construction equipment or device.

• Factory air, instrument air, nitrogen and supply line to LNG are equipped with valves and spectacle blinds between shutoff valve and our unit.

• When the units are to be repaired, checked or switched over regularly, when the equipment involved needs to be completely isolated, spectacle blinds shall be set at the shut-off valve, such as coalescence filters for feed gas, coalescence filters for purified gas, etc.

Connecting Surface of ASME B16.48 Spectacle Blind

• Raised Face 

• Male Face 

• Female Face 

• Tongue Face

• Groove Face

• Ring Joint Face

• Flat Face

Pressure Rating of ASME B16.48 Spectacle Blind

• Class 150lb

• Class 300lb

• Class 400lb

• Class 600lb

• Class 900lb

• Class 1500lb

• Class 2500lb