447Structural Bolting

2.1 General . Use the same supplier for bolts and nuts to ensure proper fit. Have the manufacturer or distributor

perform rotational -capacity (R -C) tests in accordance with Tex -452-A on all bolt, nut, and washer assemblies. Test each combination of bolt production lot, nut lot, and washer lot as an assembly and assign an R- C lot number to each lot tested. Test tw o samples from each assigned R -C lot. Furnish a manufacturer’s certified test report (MCTR) or a distributor’s certified test report (DCTR) for each R-C lot supplied. Include in the MCTR or DCTR:  results of the R -C tests,  R-C lot number,  manufacturing location for assembly components,  date and location of tests, and  a statement that the materials represented by the test report are in accordance with the specifications.

2.2 Bolt Assemblies. Provide ASTM F3125 bolts, nuts, and washers meeting the type, grade, and finish

requirements shown in Table 1, unless otherwise shown on the plans . Use Grade A325 or Grade A490 Type 3 plain (uncoated) bolts for weathering steel as specified and Grade A325 Type 1 galvanized bolts for coated steel, unless otherwise shown on the plans. Provide bolts long enough for the installed bolt end to be flush with or outside the face of the nut. Ensure galvanized nuts are lubricated with a lubricant containing a dye of a color that contrasts with the color of the galvanizing. Order ASTM A563 nuts with supplemental requirement S2 if they will be galvanized. Table 1 ASTM Type, Finish, and Grade for Structural Bolts, Nuts, and Washers ASTM Designation Bolt Type Bolt Finish ASTM A563 Nut Grade and Finish ASTM F436 Washer Type and Finish Heavy - hex holts1 A325 1 Galvanized DH2, galvanized and lubricated 1; galvanized A325 3 Plain C3 and DH3; plain and lubricated 3; plain A490 3 Plain DH3; plain and lubricated 3; plain Tension- control colts 1 F1852 1 Galvanized DH,2 galvanized and lubricated 1; galvanized F1852 3 Plain C3 and DH3; plain and lubricated 3; plain F2280 3 Plain DH3; plain and lubricated 3; plain 1. ASTM F3125 high strength structural bolts 2. ASTM A194 heavy hex Grade 2H nuts may be substituted. 674 2.3. Washer -Type Indicating Devices. Use compressible- washer type direct -tension indicators that meet ASTM F959 if allowed. Alternative washer -type indicating devices must be approved. Provide detailed testing, installation, and inspection requirements prepared by the manufacturer.

2.4 Storage . Protect all bolts and nuts from dirt and moisture at the jobsite. Remove from protected storage only

those bolts and nuts anticipated to be installed during a workday. Return unused fasteners to protected storage at the end of the day. Do not clean fasteners of lubricant present in the as -delivered condition. Perform a field R -C test at the Contractor’s expense in accordance with Tex -452-A on any lot of fasteners that shows signs of rust, dirt, or loss of lubrication as directed. Apply additional lubrication and rerun the R -C test before installing bolts if the fasteners fail the R -C test. Replace any fasteners that cannot be re-lubricated to pass the field R -C test. Tension control bolts may be re- lubricated only by the manufacturer.

2.5 Sampling and Testing. Sample high- strength bolts, nuts, and washers in accordance with Tex -719-I , when

directed. Perform field R -C tests as directed in accordance with Tex-452-A . Perform i nstallation verification tests in accordance with Section 447.4.1., “Verification Testing.”

2.6 Fitup Bolts and Erection Pins . Provide heavy -hex fitup bolts of the same diameter as the connection bolts.

Do not use washer- type indicating devices for fitups. Do not reuse galvanized bolts or Grade A490 bolts that have been used as fitup bolts. Provide enough erection or drift pins, 1/32 in. larger than the bolt diameter .

2.7 Paint Markers. Provide white or yellow paint markers for marking bolts or nuts for wrench calibration, R -C

tests, and bolt installation.

3.1 Testing Equipment . Provide a calibrated tension- measuring device (Skidmore- Wilhelm or equivalent),

calibrated torque wrench, and other accessories necessary to perform the installation verification test and the R-C test , and to calibrate hydraulic or electric torque wrenches.

3.2 Wrenches. Furnish either of the following types of wrenches.

3.2.1 Air-Driven Impact Wrenches. Furnish air- driven impact wrenches, air compressors, and related

accessories of enough capaci ty to properly tension high- strength bolts. Impact wrenches should be of enough size and capacity to be able to tension fully a bolt in less than 15 sec. Repair or replace any wrenches that are unable to apply full tension to a bolt within this time.

3.2.2 Calib rated Torque Wrenches . Furnish calibrated hydraulic or electric torque wrench and related

accessories capable of properly tensioning high- strength bolts. Calibrate the wrench to stall out or cut out completely when the bolt tension reaches 1.05 times the t ension shown in Table 2. Calibrate the wrench by tensioning three bolts of each size in a calibrated tension- measuring device (Skidmore- Wilhelm or equivalent). Mark each bolt and verify the rotation from snug- tight when calibrating the wrench in accordance with Section 447.4.5.3.1., “Turn- of-the-Nut Method.” Calibrate the wrench at least once each working day or as directed. Recalibrate the wrench for changes in bolt diameter; changes in bolt length greater than two bolt diameters; significant differences in the surface condition of the bolts, threads, nuts, or washers; or changes in the equipment or hose length.

4.1 Verification Testing . Have each member of the bolting crew that will perform the actual work complete an

acceptable pre- installation verification test in the presence of the Engineer. Only crewmembers that have demonstrated proper workmanship by verification testing may perform production bolting work.

4.1.1 Air-Driven Impact Wrench . Perform an installation verification test on three complete fastener assemblies

of each combination of diameter, length, grade, and lot to be installed before beginning bolting. Follow the bolt-tensioning procedures in accordance with Section 447.4.5.3., “Tension Bolts.” Use a calibrated tension- measuring device (S kidmore- Wilhelm or equivalent) to verify and demonstrate that the method for 675 estimating the snug- tight condition and controlling the turns from snug- tight develops a tension greater than

1.05 times the tension shown in Table 2. The snug- tight condition is defined as the tightness that exists when

the plies of the joint are in firm contact.

4.1.2 Calibrated Torque Wrench. Calibrate the wrench before beginning bolting in accordance with

Section 447.3.2.2., “Calibrated Torque Wrenches.” Use the bolting crew that wil l perform the actual work for the calibration and calibrate the wrench in the presence of the Engineer. Follow the bolt -tensioning procedures in accordance with Section 447.4.5.3., “Tension Bolts.”

4.1.3 Direct -Tension Indicator . Use a calibrated tension- measuri ng device for compression- type indicators to

verify the gap is not less than 0.015 in. or the job inspection gap specified by the manufacturer when tension in the bolt reaches 1.05 times the tension shown in Table 2. Follow the manufacturer’s instructions for pre- installation verification testing methods and frequency for alternative washer type indicating devices deemed acceptable.

4.2 Workmanship . The Engineer will disqualify any crewmembers not adhering to proper installation methods

during production work. Disqualified crew may not perform further bolting work until they complete an additional pre- installation verification test suitable to the Engineer.

4.3 General . Ensure all material within the grip of the bolt is steel. Do not allow any compressible material such

as gaskets or insulation within the grip. Ensure the slope of parts in contact with the bolt head or nut does not exceed 1:20 with respect to a plane normal to the bolt axis. Prepare all joint surfaces, including those in contact with the bolt heads, nuts, or washers , so that the surfaces are free of dirt, loose rust, loose mill scale, burrs, and other matter that would prevent solid seating of the parts. Replace any bolts and nuts installed for shipping purposes unless the shop drawings specify the shop- installed bolts are to be fully tensioned in the shop. Do not tension bolts that have been installed snug- tight in the shop. Remove any bolts installed snug -tight in the shop and replace them with new bolts. Inspect and prepare the joint surfaces after removing shop- installed bolts that are not fully tensioned in the shop. Provide a hardened washer for heavy -hex and tension- control bolts under either the nut or the bolt head, whichever is turned during tensioning. Install hardened washers under both the nut and bolt head of Grade A490 bolts when the outer plies being fastened have a yield strength less than 40 ksi. Install an ASTM F436 washer for direct -tension indicators as follows:  under the nut when the nut is turned and the direct -tension indicator is located under the bolt head,  between the nut and the direct -tension indicator when the nut is turned and the direct -tension indicator is located under the nut ,  under the bolt head when the bolt head is turned and the direct -tension indicator is located under the nut, and  between the bolt head and the direct -tension indicator when the bolt head is turned and the direct -tension indicator is located under the bolt head. Tension all bolts to provide the minimum bolt tension values shown in Table 2. Erect steel in accordance with Item 441, “Steel Structures.” Do not tack -weld any parts to eliminate fitup bolts or to hold parts together while bolting. Remove lubricant from bolt assemblies on painted structures after tensioning and before coating the connections. Re-tighten the nuts or tack weld the nuts to the bolts when bolts are us ed to temporarily support welded diaphragms after completing the welding operations if the diaphragms are over vehicular or pedestrian traffic. 676 Table 2 Bolt Tension Nominal Bolt Size, in. Minimum Tension (kips) Grade A325 Bolts Grade A490 Bolts 1/2 12 15 5/8 19 24 3/4 28 35 7/8 39 49 1 51 64 1-1/8 64 80 1-1/4 81 102 1-3/8 97 121 1-1/2 118 148

4.4 Preparation of Faying Surfaces . Perform blast cleaning or painting of faying surfaces in accordance with

Item 441. Provide an AMPP- SP 10 blast cleaning before shipment for weathering steel. Do not wire- brush weathering steel faying surfaces.

4.5 Bolt Installation . Use the following procedure for bolt installation of a complete connection.

4.5.1 Fair-Up Holes . Use a minimum number of erection or drift pins, as directed, in the holes to “fair -up” all holes.

4.5.2 Install Bolts . Install bolts in all remaining holes of the connection. Do not use excessive force, which could

result in damage to the threads, to install the bolts. Increase the number of erection or drift pins as necessary to align the holes if force is required to install the bolts. Do not ream the holes unless approved. Ream the holes in accordance with Section 441.3.11.5., “Misfits,” if approved. Remove the erection or drift pins and install bolt s in these holes. Bring the connection to a full snug- tight condition by snugging systematically from the most rigid part of the connection to the free edges. The snug- tight condition is defined as the tightness that exists when the plies of the joint are in firm, full contact and all of the bolts in the joint have been tightened enough to prevent the removal of the nuts without the use of a wrench. A snug- tight condition can usually be attained by a few impacts of an impact wrench or the full effort of a w orker using an ordinary spud wrench, as demonstrated in the installation verification test. As necessary, re- snug previously snugged bolts that may have relaxed due to the subsequent snugging of adjacent bolts to ensure all bolts are simultaneously snug- tight and the connection plates are in full contact. Fully tighten a minimum number of bolts as directed until the plies are in full contact if snugging does not bring the plies of the joint into full contact. Mark these bolts as fitup bolts. Use a non- galvanized Grade A325 bolt of the same diameter as a fitup bolt in connections requiring the use of galvanized Grade A325 bolts. Re-snug all remaining bolts . Do not use washer -type indicating devices to bring the connection to a snug- tight condition. Rather, install heavy -hex bolt assemblies in enough holes (approximately 20%) to attain firm, full contact between plies. Remove the heavy -hex bolts and install the washer -type indicating device assemblies after firm contact is established by connections in surrounding bolt holes.

4.5.3 Tension Bolts . Loosen all fitup bolts after tensioning all the other bolts in the connection. Ungalvanized

Grade A325 bolts used as fitup bolts may be reused in a connection using this type of bolt. Replace all galvanized bolts and Grade A490 bolts used as fitup bolts. Tension these remaining untensioned bolts in accordance with this Section. Ensure the element not turned by the wrench (bolt head or nut) does not rotate . 4.5.3.1. Turn- of-the-Nut Method. Match -mark the nuts and the protruding bolt ends after the bolts have been brought up to snug- tight condition and before final tensioning so that actual rotation can be determined. Tension all bolts in the connection to their final tension by the amount of rotation shown in Table 3. Start final tensioning at the center or most rigid part of the connection and progress toward the free edges. 677 4.5.3.2. Calibrated Wrench Method. Use a calibrated hydraulic torque wrench to tension all bolts to 1.05 times the tension shown in Table 2 after they have been brought to the snug-tight condition. Calibrate the wrench in accordance with Section 447.3.2.2., “Calibrated Torque Wrenches.” Start tensioning at the most rigid part of the connection and proceed to the free edges. Return the wrench to re- tension previously tensioned bolts that may have relaxed due to the subsequent tensioning of adjacent bolts. Place marks on the socket at one-third points so the amount of rotation can be visually determined. 4.5.3.3. Washer -Type Indicating Devi ces. 4.5.3.3.1. Compressible- Washer Type , Direct -Tension Indicators . Ensure the direct -tension indicator arches are oriented away from the work and that they bear against the hardened bearing surface. Confirm the appropriate feeler gau ge is accepted in at least half the spaces between protrusions before tensioning and refused entry in at least half the spaces between protrusions after tensioning. 4.5.3.3.2. Alternative Washer Type Indicating Devices. Follow the procedures prepared by the manufacturer and approved. Verify proper installation after tensioning.

4.5.4 Bolt Reuse . Do not reuse Grade A490 or galvanized Grade A325 bolts. Ungalvanized Grade A325 bolts

may be reused once if the threads have not been damaged. Re- tensioning previously tensioned bolts loosened by the tensioning of adjacent bolts is not considered to be reuse. Tension all bolts in a connection within 10 days of installation. Bolts not tensioned within 10 days of installation are subject to field R -C testing. Re -lubricate or replace any installed bolts that do not ha ve enough lubrication as determined by the field R -C test. Table 3 Nut Rotation from Snug -Tight Condition1 Bolt Length (underside of head to end of bolt) Disposition of Outer Face of Bolted Parts Both Faces N ormal to Bolt Axis One Face Normal to Bolt Axis and Other Face Sloped Less than 1:20 (beveled washer not used) Both Faces Sloped Less than 1:20 from B olt Axis (beveled washer not used) Up to and including 4 bolt diameters 1/3 turn 1/2 turn 2/3 turn Over 4 bolt diameters up to and including 8 diameters 1/2 turn 2/3 turn 5/6 turn Over 8 bolt diameters up to and including 12 diameters2 2/3 turn 5/6 turn 1 turn 1. Nut rotation is relative regardless of the element (nut or bolt) being turned. The tolerance is –0°, +30° for bolts installed by 1/2 turn or less and – 0°, +45° for bolts installed by 2/3 turn or more. 2. Determine the required rotation for bolt lengths greater than 12 diameters using the installation verification test in a simulated connection of solidly fitted steel.