Commonwealth of Pennsylvania
Department of Transportation
PA Test Method No. 429
October 2013
7 Pages
LABORATORY TESTING SECTION
Method of Test for
HIGH STRENGTH BOLT INSPECTION TESTING
1.
SCOPE
1.1
This method of test is in accordance with AASHTO M-164 (ASTM A 325), and
AASHTO M-253 (ASTM A-490). Additional requirements of the 1996 supplement AASHTO
Division II, Section 11.5.6.4.9, cover the procedures for final field inspection or shop testing of
black or galvanized bolt, nut and washer assemblies.
1.2
Perform calibration at least once each inspection day (torque/tension relationship).
1.3
Washers or steel spacers are required behind nuts for all tests, even if not required
on the plan (prevents face plate wear of the testing device).
1.4
Determine a job inspection torque for all representative combinations,
(grade/size/condition) of Bolt/Nut/Washer assemblies as those under inspection. Do not reuse
assemblies that have been tested in the installation process.
2.
1.5
Assign an inspection lot number that coincides with each assembly in the section.
1.6
Test a minimum of three assemblies per inspection lot.
EQUIPMENT REQUIRED
2.1
Use a Skidmore- Wilhelm Calibrator (Skidmore) or an acceptable equivalent
device with proof of calibration within the last year. For bolts that cannot be assembled in the
Skidmore test device, see Section 4 for the proper procedure.
2.2
Use a calibrated manual dial torque wrench with a 1355 N∙m (1000 Ft.-lb.)
capacity or a torque multiplication device with proof of calibration within the last year.
2.3
Use steel spacers and/or washers with a hole diameter a maximum 1.59 mm
(1/16") greater than the diameter of bolt to be tested.
2.4
Use a rigid steel section upon which to mount the Skidmore test device. The
flange of girders or cross frames, accessible from the ground, is satisfactory.
2.5
Use bolts, nuts, and washers (if used) having lubrication characteristics similar to
the installed bolts.
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October 2013
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3.
PROCEDURE FOR LONG BOLTS IN THE SKIDMORE
3.1
Test three bolt, nut, and washer assemblies from each inspection lot. Install the
nut on the bolt. Measure the length of bolt remaining when 3 to 5 full threads of the bolt are
located between the bearing face of the nut and the bolt head. Measure the effective bolt length,
(the distance from the end of the threaded shank to underside of the bolt head).
3.2
Place the bolt in the Skidmore. Use steel shims or washers to take up any space,
if necessary to produce the same length measured in Section 3.1 above. Tighten each bolt by any
convenient means to the specified tension (see Table 2 for values).
3.3
Apply an inspection wrench to the tightened bolt to determine the torque required
to turn the nut head 5 degrees (approximately 25.4 mm (1") at a 304.8 mm (12") radius) in the
tightening direction.
3.4
The average of the torques required for all three bolts shall be taken as the jobinspection torque.
3.5
Select ten percent (at least two per connection) of the tightened bolts on the
structure represented by the test bolts in each connection.
3.6
Apply job-inspection torque in the tightening direction to each of the selected
bolts using the inspection wrench.
3.7
If none of the selected bolt nuts or heads turn under the job-inspection torque,
consider the bolts in the connection to be properly tightened.
3.8
If the application of the job-inspection torque turns one or more bolt heads or
nuts, apply the job-inspection torque to all bolts in the connection. Tighten and reinspect bolts
whose head or nut turns under the job-inspection torque. The Contractor may, however, retighten
all the bolts in the connection and resubmit it for inspection, under Sections 3.5 to 3.8, so long as
bolts are not overtightened or damaged by this action.
3.9
4.
Record all test results on Attachment 1 of this procedure.
PROCEDURE FOR BOLTS THAT CANNOT BE ASSEMBLED IN THE SKIDMORE
Note 1 - Bolt assemblies that cannot be assembled in the Skidmore may be tested in a
steel section with the hole diameter in the plate being a maximum 1.59 mm (1/16 in.) greater
than the bolt diameter. The turn Test Tension requirement of Table 2 does not apply.
4.1
Test three bolt, nut, and washer assemblies from each inspection lot. Install the
nut on the bolt and measure the length of bolt when 3 to 5 full threads of bolt are located between
the bearing face of the nut and the bolt head.
PTM No. 429
October 2013
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4.2
Choose a steel section with the proper size hole to install the bolt. Any available
splice hole can be used with a plate thickness that will provide the required number of threads
under the nut.
4.3
Install the bolt and use appropriate shims to produce the thread stick out measured
in Section 4.1.
4.4
Install the nut and washer using a second wrench to prevent the bolt head from
turning at all times.
4.5
Tighten the nut snug tight (approximately 75-100 ft-lb). Mark reference points on
the socket, nut, bolt, and steel plate and turn the nut using a torque wrench to the minimum
rotation required for turn of the nut installation in Table 1. Apply the inspection wrench in the
tightening direction to the tightened bolt to determine the torque required to turn the nut head 5
degrees (approximately 25.4 mm (1") at a 304.8 mm (12") radius). Torque must be measured
with the nut in motion. Record the torque.
Table 1
4.6
through 3.8.
4.7
Bolt Length
(measured in
Section 4.1)
≤ 4 x Bolt
Diameter
>4 ≤ 8xBolt
Diameter
Required Rotation
1/3
1/2
Continue inspection by following the procedures as described in Sections 3.4
Record all test results on Attachment 1 of this procedure.
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October 2013
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TABLE 2
REQUIRED FASTENER TENSION
MINIMUM BOLT TENSION IN KN (POUNDS)
Bolt Size
mm (inches)
12.7 (½)
15.9 (⅝)
19.1 (¾)
22.2 (⅞)
25.4 (1)
28.6 (1⅛)
31.8 (1¼)
34.9 (1⅜)
38.1 (1½)
AASHTO M-164
ASTM A 325
53.4 (12,000)
84.5 (19,000)
124.5 (28,000)
173.5 (39,000)
226.8 (51,000)
249.1 (56,000)
315.8 (71,000)
378.1 (85,000)
458.1 (103,000)
AASHTO M-253
ASTM A 490
66.7 (15,000)
106.7 (24,000)
155.7 (35,000)
218.0 (49,000)
284.7 (64,000)
355.8 (80,000)
453.7 (102,000)
538.2 (121,000)
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October 2013
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ATTACHMENT 1
COUNTY ___________ S.R.___________ SECTION __________DATE ___________
Structure No. S-____________
================================================================
Has the pre-installation process been verified?_____________________________________
What installation process was used?__________________________________________
Was it done correctly and documented?_______________________________________
================================================================
High Strength Bolts Inspection Testing
1. Bolt: _____A 325 _____A 490
Inspection Lot # __________
Galvanized: _____Yes _____No
Condition: _______________
2. Manufacturer:
Bolt
_______________
Length _____in.
Diameter _____in.
Nut
_______________
Washer
_______________
3. Specified Tension (Table 2- Typical) __________ kips
Note: Specified tension N/A for short bolts. Rotation in accordance with Table 1.
Sample 1
Sample 2
Sample 3
4. Measured Torque __________ ft-lbs __________ ft-lbs __________ ft-lbs
(Torque measured with a required nut turn of 5 degrees in the tightening direction.)_____Yes
5. Average Torque (Job Inspection Torque)
Note: See Field Book # __________ Page _____
Connection Description:
6.
__________ ft-lbs
Ten percent (at least two) bolts per connection verified with the inspection torque
wrench? _____ Yes _____ No
7. Did any selected bolt or nut head assemblies turn in the connection under the job-inspection
torque? _____Yes _____No (If no, consider the connection to be properly tightened. If yes go
to question 8 or 9).
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October 2013
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8. Was the job-inspection torque applied to all bolts or nuts in the affected connections?
_____ Yes ____ No ____N/A
8A. Were all bolts that turned retightened?
_____ Yes ____ No ____N/A
8B. Were all bolts re-inspected and found not to turn?
_____ Yes ____ No ____N/A
( If all of the questions in # 8 are answered yes, consider the connection to be properly
tightened).
or
9. At the option of the Contractor were all of the bolt assemblies in the connection retightened
that were found to turn.?
_____ Yes _____No _____N/A
9A. Were all bolts that turned retightened?
_____Yes _____No _____N/A
9B. Were all bolts re-inspected and found not to turn?
_____Yes _____No _____N/A
(If all of the questions in #9 are answered yes, consider the connection to be properly tightened).
Tested by:_________________________________________
Witnessed by:______________________________________
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October 2013
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