FIELD BOLTING WITH TORQUE WRENCH (CALIBRATED WRENCH) Per AISC 14th Edition

THE NEXT PANES ARE EXAMPLES

MILL CERTS 16.2-5 (2.1) Manufacturer certifications for all fastener

components used in the fastener assemblies shall be available to the E.O.R. and inspector prior to assembly or erection of structural steel.

Commentary: Certification by the manufacturer or supplier of high-strength bolts, nuts, washers and other components of the fastener assembly is required to ensure that the components to be used are identifiable and meet the requirements of the applicable ASTM Specification.

A325 GALVANIZED BOLT MILL CERT WITH ID MARKS

NUT MILL CERT WITH ID MARKS (WAXED NUT)

RECEIVED NUTS AND BOLTS AT JOB SITE

LABEL SHOWING SIZE & LOT NUMBER

NUT/WASHER GRADE, FINISH AND IDENTIFICATION 16.2-7 (Table 2.1) The attached table on the following page indicates

that an A325 bolt (Type 1 Galvanized finish) with an A563 NUT (DH galvanized and lubricated) and a F436 washer (Type 1; galvanized).

Note: In note ‘c’ the substitution of ASTM A194 grade 2H nuts in place of ASTM A563 grade DH nuts is permitted.

MARKINGS/IDENTIFICATION 16.2-8 (Figure C-2.1)

Commentary: Regular heavy-hex structural bolts and twist off type TC bolt assemblies are required by ASTM Specifications to be distinctively marked. Certain markings are mandatory. In addition to the mandatory markings, the manufacturer may apply additional distinguishing markings.

THE NEXT PANE IS AN EXAMPLE

STORAGE

16.2-5 (2.2) Commentary Protected storage requirements are specified for high-strength bolts, nuts,

washers and other fastener components with the intent that the condition of the components be maintained as nearly as possible to the as-manufactured condition until they are installed in the work. This involves:

The storage of the fastener components in closed containers to protect from dirt and corrosion;

The storage of the closed containers in a protected shelter; The removal of fastener components from protected storage only as

necessary; and, The prompt return of unused fastener components to protected storage. Note: in 16.2-10 commentary states that “Containers of fasteners with hot-

wax type lubricants should not be subjected to heat that would cause depletion or change in the properties of the lubricant.”

FASTENERS IN PROTECTED STORAGE

16.2-9 Commentary Galvanized high-strength bolts and nuts must be considered as a manufactured

assembly. Insofar as the hot dipped galvanized bolt and nut assembly is concerned, four principal factors must be considered so that the provisions of this Specification are understood and properly applied. These are:

The effect of the hot dip galvanizing process on the mechanical properties of high strength steels;

The effect of over-tapping for hot dipped galvanized coatings on the nut stripping strength;

The effect of galvanizing and lubrication on the torque required for pretensioning; and, Shipping requirements. (Birkemoe and Herrsschaft 1970) commentary, “Thus, it is required in ASTM A325 that a

galvanized bolt and lubricated galvanized or Zn/Al inorganic coated nut be assembled in a steel joint with equivalently coated washer and tested by the supplier prior to shipment. This testing must show that the galvanized or Zn/A inorganic coated nut with the lubricant provided may be rotated from the snug tight condition well in excess of the rotation required for pretentioned installation without stripping. This requirement applies to hot dipped galvanized, mechanically galvanized, and Zn/Al inorganic coated fasteners.” The above requirements clearly indicate that

1. Galvanized and Zn/Al inorganic coated high strength bolts and nuts must be treated as a fastener assembly;

2. The supplier must supply nuts that have been lubricated and tested with the supplied high strength bolts;

3. Nuts and high strength bolts must be shipped together in the same shipping container; and,

4. The purchase of galvanized high strength bolts and galvanized nuts from separate suppliers is not in accordance with the intent of the ASTM Specifications because the control of over tapping, the testing and application of lubricant and the supplier responsibility for the performance of the assembly would clearly not have been provided as required.

USE OF WASHERS IN PRETENSIONED AND SLIP CRITICAL JOINTS 16.2-44 (6.2.1) Calibrated wrench pretensioning (Torque wrench); When the calibrated wrench method is used, an ASTM F436 washer shall be used under the turned element.

16.2-45 (6.2.5) Oversized or slotted hole: When an oversized hole occurs in an outer ply, the washer requirements shall be given in Table 6.1. The washer used shall be of sufficient size to completely cover the hole.

1 PRE-INSTALLATION VERIFICATION 16.2-47 (7.1) Tension calibrator / Skidmore A tension calibrator shall be used where bolts are to be installed in pretensioned joints and slip critical joints to: (1) Confirm the suitability of the complete fastener assembly, including lubrication, for

pretensioned installation; and, (2) Confirm the procedure and proper use by the bolting crew of the pretensioning method used. Commentary: A tension calibrator is a device that indicates the pretension that is developed in

a bolt. It must be readily available whenever high strength bolts are to be pretensioned. A bolt tension calibrator is essential for:

(1) The pre-installation verification of the suitability of the fastener assembly, including the lubrication that is applied by the manufacturer or specially applied, to develop the specified minimum pretention;

(2) Verifying the adequacy and proper use of the specified pretentioning method to be used; (3) Determining the installation torque for the calibrated wrench pretensioning method; and, (4) Determining an arbitration torque as specified in Section 10, if required to resolve dispute.

(1) Table 7.1 for use with Skidmore (16.2-48)

REQUIRED TESTING

16.2-49 (7.2) A representative sample of not fewer than three complete fastener assemblies of each combination of diameter, length, grade and lot to be used in the work shall be checked at the site of installation in a tension calibrator (Skidmore) to verify that the pretensioning method develops a pretension that is equal to or greater than that specified in Table 7.1. Washers shall be used in the pre-installation verification assemblies as required in the work in accordance with the requirements in Section 6.2.

16.2-55 (8.2.2) Calibrated wrench pretensioning: The pre-installation verification procedures specified in Section 7 shall be performed daily for the calibration of the installation wrench (Torque wrenches). Torque values determined from tables or from equations that claim to relate torque to pretension without verification shall not be used. (See next slide)

SAMPLES TAKEN FROM RECEIVED LOTS OF NUTS, BOLTS AND WASHERS

AISC 16.2-61 (9.2.2) Calibrated wrench pretensioning: The inspector shall observe the pre-installation verification testing required in Section 8.2.2. Subsequently, it shall be insured by routine observation that the bolting crew properly applies the calibrated wrench (torque wrench) to the turned element. No further evidence of conformity is required. A pretension that is greater than the value specified in Table 8.1 shall not be cause for rejection.

THE NEXT PANES ARE PHOTOS OF A TENSION CALIBRATOR (SKIDMORE), SET-UP FOR DAILY TESTING OF BOLTS AND VERIFICATION OF TORQUE WRENCHES, PER AISC 16.2 (8.2.2)

TORQUE WRENCHES WITH CERTIFICATES

TORQUE WRENCH CALIBRATION CERTIFICATE

The AISC Manual is a valuable tool for Inspectors, Engineers, Jurisdiction Officials and Clients.

This presentation was intended as an overview and should not be substituted for the actual code.

It is also important to note that this presentation showed bolt tensioning using torque wrenches. Bolt tensioning by the Turn of Nut has similarities but has substantial differences, but the receiving, identification and storage of fasteners is the same.

Advanced Special Inspection would like to thank you for taking the time to view this presentation and welcome any questions you might have about your particular project.