Technical Specification TS3 – Tightening Procedure for high strength steel bolts Part-turn Method

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TS3 – Tightening procedure for high strength steel bolts

DOCS 826854v3 2

Document Control Document owner: Operations & Engineering Manager

Change Control Policy

Any amendment to this standard must be recorded in the table below.

If substantial changes are made a new version of the document shall be created to preserve an audit trail.

Review Date Author Description of amendments

A 15/07/2009 T. Tyler Reformatting.

B 20/7/2009 T. Tyler Previously TS 7

C 20/4/2009 T. Tyler Re-brand

D 17/11/2014 J. McMiles Updates styling and formatting.

TS3 – Tightening procedure for high strength steel bolts

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Contents 1. Scope 4

2. General 4

3. Assembly Procedure 4

4. Tightening Procedure 5

5. Inspection 6

TS3 – Tightening procedure for high strength steel bolts

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1. Scope This Specification covers the tightening and inspection procedures to be adopted in tightening High-Strength steel bolts using the part-turn methods.

The governing Australian Standards shall be the current issues and amendments of AS 4100 and AS/NZ 1252.

2. General The system of part-turn tightening shall be adopted, and shall be carried out in accordance with the following procedure. The provisions laid down in AS 4100 for part-turn tightening shall generally apply.

3. Assembly Procedure 3.1 Ensure nuts be placed so that the mark specified in AS/NZS 1252 to identify a high strength

nut is visible after tightening.

3.2 Ensure contact surfaces are clean and free from defects.

3.3 Packing shall be provided wherever necessary to ensure that the load transmitting plies are in effective contact when the joint is tightened to the snug tight condition defined in Clause 15.2.5.2(a). All packing shall be steel with a surface condition similar to that of the adjacent plies.

3.4 Line up holes with enough drift pins to maintain dimensions and plumbness of the structure. Pins should not be removed until bolts in balance of holes have received final tightening.

3.5 Install bolts in the remaining holes, one washer only required to be placed under the rotating component. Taper washers should be used where slope on any surface exceeds 3° and where possible shall be placed under the non-rotating component. The nut shall be placed so that the mark specified in AS 1252 to identify a high strength nut, is visible after tightening.

3.6 Snug-tightening and final tensioning of the bolts in a connection shall proceed from the stiffest part of the connection towards the free edges. High strength structural bolts that are to be tensioned may be used temporarily during erection to facilitate assembly, but if so used they shall not be finally tensioned until all bolts in the connection have been snug tightened in the correct sequence.

3.7 Re-tensioning of bolts which have been fully tensioned shall be avoided, except that if re-tensioning is carried out, it shall only be permitted once and only where the bolt remains in the same hole in which it was originally tensioned and with the same grip. Re-tensioning of galvanized bolts shall not be permitted. Under no circumstances shall bolts which have been previously tensioned be reused in another hole. Touching up or re-tensioning of previously tensioned bolts which may have been loosened by the tensioning of adjacent bolts shall not be considered as re-tensioning.

TS3 – Tightening procedure for high strength steel bolts

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4. Tightening Procedure

MINIMUM BOLT TENSION TABLE Nominal Diameter of Bolt Minimum Bolt Tension kN

M16 95

M20 145

M24 210

M30 335

M36 490

Note: The minimum bolt tensions given in this table are approximately equivalent to the minimum proof loads given in AS/NZS 1252.

4.1 On assembly, all bolts in the connection shall be first tightened to a snug-tight condition to ensure that the load transmitting piles are brought into effective contact. Snug-tight is the tightness attained by a few impacts of an impact wrench or by the full effort of a person using a standard podger spanner.

4.2 After completing snug-tightening, location marks shall be established to mark the relative position of the bolt and the nut and to control the final nut rotation. Observation of the final nut rotation may be achieved by using marked wrench sockets, but location marks shall be permanent when required for inspection.

4.3 Bolts shall be finally tensioned by rotating the nut by the amount give in the Minimum Bolt Tension Table above. During the final tensioning, the component not turned by the wrench shall not rotate.

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NUT ROTATION FROM THE SNUG-TIGHT CONDITION TABLE

Disposition of Outer Face of Bolted Parts (see Notes 1,2,3 &4)

Bolt Length (underside of head

to end of bolt)

Both Faces Normal to Bolt Axis

One Face Normal to Bolt Axis and Other

Sloped

Both Faces Sloped

Up to and Including 4 Diameters

1/3 Turn 1/2 Turn 2/3 Turn

Over 4 Diameters but not Exceeding 8

Diameters

1/2 Turn 2/3 Turn 5/6 turn

Over 8 Diameters but not Exceeding 12

Diameters (see Note 5)

2/3 Turn 5/6 Turn 1 Turn

Notes:

1. Tolerance on rotation for 1/2 turn or less, 1/12 of a turn (30°) over and nil under tolerance, for 2/3 turn or more, 1/8 of a turn (45°) over and nil under tolerance.

2. The bolt tension achieved with the amount of nut rotation specified in Nut Rotation from the Snug-Tight Condition Table will be at least equal to the minimum bolt tension specified in the Minimum Bolt Tension Table.

3. Nut rotation is the rotation relative to the bolt, regardless of the component turned.

4. Nut rotations specified are only applicable to connections in which all material within the grip of the bolt is steel.

5. No research has been performed to establish the turn-of-nut procedure for bolt lengths exceeding 12 diameters. Therefore the required rotation should be determined by actual test in a suitable tension measuring device which simulates conditions of solidly fitted steel.

5. Inspection 5.1 The Contractor shall ensure that the assembly and tightening procedures have been carried

out in accordance with this Specification. Bolts and nuts which, on visual inspection, show any evidence of physical defects shall be removed and replaced.

5.2 The Contractor shall determine the number of bolts to be checked in each connection. A suitable sample would consist of 10 percent of the bolts but not less than two bolts selected at random at each joint.

5.3 Final inspection of bolt tightness by the use of an "Inspection Wrench" is left to the discretion of the Engineer. This method shall be in accordance with AS 1511.

Any such inspection by the Engineer shall in no way relieve the Contractor of his responsibility as detailed in Clauses 5.1 and 5.2 of this Specification.