The suction and discharge pipe connections must be carefully made so as
to prevent putting excess stress on either the piping or pump flanges.
Incorrect joints lead to problems like leak, creating unplanned down
time. As such, fasteners must be the correct grade for the application.
Flange bolts are used in such circumstances.
bolts are those type of bolts having a ridge or skirt around the bolt
head. They are also know as frame bolts and are designed to provide the
holding power as if a washer was installed. The skirt is the
distributing agent of the entire clamping load. Pipe flange bolts are
widely used in various applications, especially pipe fittings and
plumbing. With their multi-feature function, they help make jobs easier
and faster. Pipe flange bolts are made from a variety of types and
grades to suffice for the various applications flange bolts are used.
- Alloy steel
- Stainless steel
- Carbon steel
- Cast iron
- Bronze etc.
How to tighten pipe flange bolts?
Final torque for the pipe flange bolts is dependent on the type of
gasket used. This torque provides the clamp load on the gasket needed
for proper sealing. Metallic and spiral type gaskets require greater
clamping force than flat rubber gasket material. Higher system pressures
lead to increased fastener torques. Pipe flange gaskets are never be
used to pull the piping up to the pump. This can stretch the bolt, bend
a pipe flange, break the pump casting or bend a suction plate. Rather,
pipe flange bolts can fill the gap between the pump and spool piece by
using the correct tightening sequence. Pipe flange bolts should be
tightened in the correct sequences as illustrated below.
should be a sufficient number of steps to bring the flanges together and
achieve the torque required by the gasket. Four and eight pipe bolt
flanges are tightened in a cross manner. For large flanges with 12 or
more fasteners, it is suggested that two workers tighten the bolts at
the same time, working 180 degree apart. Each worker tightens bolt
number one in quadrant A, then bolt number one in quadrant B, then move
to bolt number two. This process is repeated till the required torque is
achieved on all the fasteners. Thus, pipe flange bolts reduces excess
localized loading on the flange components and gasket.