What is the proper sequence to use when tightening flange bolts?

What is the proper sequence to use when tightening flange bolts?

Tightening sequence. The first pass, lightly tighten the first bolt then move directly across or 180 degrees for the second bolt, then move1/4 turn around the circle or 90 degrees for the third bolt and directly across for the fourth. Continue this sequence until all bolts are tightened.

What is a torque sequence?

Bolt tightening sequence, or torque sequence, is defined in the torque tightening procedure. Flange joints are torqued tight with the help of a torque wrench (manual or hydraulic). Torque bolts and nuts in a “CRISS-CROSS” sequence using a minimum of three torquing passes and the maximum bolt stress as defined.

How do you torque a flange?

Ensuring proper flange alignment….First to half torque and second to final torque.

1. Put the socket on the head of the wrench.
2. Turn the nut by hand until it catches the screw threading.
3. Turn the handle clockwise to tighten the nut.
4. Stop turning the wrench when it stops clicking or moving.

Why is torque sequencing used on flanges?

Flange joints require proper tightening to avoid the leak of the fluid from the joint. Bolt tightening sequence or torque sequence is defined in the torque tightening procedure. Most company has their Flange bolt torque tightening procedure that used during construction and operation of the plant.

When torquing a flange Why is it important to use a proper tightening sequence?

Bolt / Stud Tightening Pattern One of the most difficult jobs is to produce the correct assembly pressure on the gasket, low enough to avoid damaging the gasket, but high enough to prevent a leak in the seal. It is vitally important to control accurately the amount of force applied to any particular flange arrangement.

How is flange bolt torque calculated?

Using a calibrated torque wrench (Manual or Hydraulic Torque Wrench), flange bolt torque can be measured during flange assembly….Applied Torque, T= (k∙f∙d)/12 in FPS Unit

1. T=Torque in ft-lb.
2. k=Dimensionless nut factor or tightening factor.
3. f=axial force in pounds.
4. d=Nominal bolt diameter in inches.

How do you calculate torque sequence?

Begin with the formula T = K x U x D x P, where T is the torque, K is a standard representing 1.33, U is the coefficient of friction, D is the diameter of the fasteners, and P is the necessary preload.

Why do we use torque in sequences?

Bolt tightening sequences are when an arrange of bolts are tightened in a pattern to the required torque. The sequence the bolts are tightened is a symmetrical pattern to reduce the amount of pre-load lost in a bolt, as a result of elastic interactions. Torque is normally applied to a bolt using a torque wrench.

How tight should flange bolts be?

You’re trying to avoid bowl movement, so that it doesn’t shift or fall over, not to hold the floor up by the toilet bolts. As tight as you can go will probably snap the porcelain (with a good socket you can torque a nut onto a bolt quite a bit). Until you think it’s about to snap is just guessing. Snug.

Where should a flanged fitting be loosened first?

By reaching over the pipe to first loosen flange bolts on the far side, if any pressure happens to be inside the pipe, it should leak there first, venting the pressure in a direction away from you.

How do you calculate flange force?

Following are typical flange forces to consider in determining a gasket solution.

1. Bolt-up force.
2. This is the force intended when the BFC is initially tightening.
3. Fbu = T × 1000/(k d nom) SI Units.
4. The total force on the flange from bolt-up becomes the force of a given bolt times the number of bolts.
5. FTbu = Fb × Bno.

What are the factors that determine a torque?

Expert Answer:

• The factors on which the turning effect of force or torque acts are:
• – The magnitude of the applied force.
• – The distance of the line of action of force from the point of rotation of that body.

Which is the correct torque sequence for a flange bolt?

Flange Bolt Torque Sequence. PASS 2: Torque to a maximum of 60% of the final torque value. PASS 3: Torque to the final torque value (100%). After the three basic torque passes are completed, repeat torquing the nuts at least once using the final torque in a “CRISS-CROSS” manner until no further rotation of the nut is observed. For easy handling,…

When to use hydraulic Torquing on a flange bolt?

To achieve the benefits of the pre-loading, the clamping force in the screw must be higher than the joint separation load. When the bolt loading requires a torque higher than 678 Nm (500 ft-lbs.) to be applied, hydraulic bolt torquing is recommended.

Which is the best bolting pattern for torquing a gasket?

While the Star Pattern is the most common, it is certainly not the only — or necessarily the best — bolting pattern to apply when torquing a bolted flange assembly. In fact, there is no “silver bullet” bolt tightening sequence ideal for torquing every type of flange or gasket.

How many torquing passes in a criss-cross torque sequence?

Torque bolts and nuts in a “CRISS-CROSS” sequence using a minimum of three torquing passes and the maximum bolt stress as defined. PASS 1 Torque Sequence: Torque to a maximum of 30% of the final torque value in accordance with the torque sequence.