ASTM A307
Carbon Steel Bolt and Rod Tensile Test

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 23, 2026

ASTM A307 is the specification for low-carbon steel bolts, studs and threaded rod from ¼ in. through 4 in. diameter with a 60,000 psi (≈ 414 MPa) minimum tensile strength. The current edition is A307-21, which replaced A307-14. It is maintained by ASTM Committee F16 on Fasteners and is written in inch-pound units only; there is no A307M.

A307 is a product specification. It sets the chemistry, hardness, full-size breaking loads, threads, marking and inspection rules. The test methods themselves are in ASTM F606/F606M, which A307 references directly. This guide covers both halves: what an A307 bolt has to meet, and how to actually test one in the lab, with the full-size loads converted to kN and machine sizing based on the loads bolts really reach, not just the minimums.

It is written for fastener manufacturers and importers, distributors who issue certs, third-party test labs, receiving inspection at fabricators and EPC contractors, and piping contractors who still bolt up cast-iron flanges.

ASTM A307 at a glance

Current edition: A307-21 (first approved 1947)
Scope: carbon steel bolts, studs and threaded rod, ¼ in. through 4 in. diameter
Grades: Grade A (general purpose) and Grade B (flanged joints with cast-iron flanges). Grade C was removed in 2007 and replaced by ASTM F1554 Grade 36
Tensile strength: Grade A 60 ksi (414 MPa) minimum; Grade B 60–100 ksi (414–690 MPa)
Yield strength: no requirement for Grade A or Grade B
Elongation: 18 % minimum in 2 in., machined specimens only
Reduction of area and impact toughness: no requirement
Hardness: Grade A 121–241 HB (69–100 HRB); Grade B 121–212 HB (69–95 HRB)
Test methods: ASTM F606/F606M. Wedge tension for square and hex heads; axial tension for other heads, studs and threaded rod
Full-size tension test: required through 1½ in.; machined specimens allowed above 1½ in.
Threads: UNC Class 2A per ASME B1.1; threaded rod per ASME B18.31.3
Nuts: ASTM A563 Grade A (hex or heavy hex depending on grade and size)
Coatings: hot-dip zinc per F2329/F2329M or mechanical zinc per B695 Class 55
Head marking: manufacturer ID plus “307A” or “307B”

Grades A, B and the retired Grade C

Grade A is the general-purpose grade: bolts, studs and threaded rod with a 60 ksi minimum tensile strength and no upper limit. It is what you get if the purchase order does not name a grade. Grade A bolts are hex-head per ASME B18.2.1.

Grade B is intended for flanged joints in piping systems with cast-iron flanges. It has the same 60 ksi minimum but adds a 100 ksi maximum, a tighter sulfur limit (0.05 % versus 0.15 %), a lower hardness cap (95 HRB versus 100 HRB) and heavy hex heads. Threaded rod is not normally made to Grade B unless the purchaser asks for it. The standard does not spell out why the ceiling exists, but the usual reading is that capping bolt strength keeps a heavily torqued bolt from overloading a brittle cast-iron flange before the bolt itself yields.

What happened to Grade C

Grade C covered non-headed anchor bolts with a 36 ksi minimum yield. It was removed from A307 in 2007, and the scope now simply says it was replaced by ASTM F1554 Grade 36. Many supplier charts and test-lab pages still show a Grade C row with active values; that information is out of date. Legacy Grade C anchor bolts were identified by a green-painted projecting end, which you may still see on older jobs.

The anchor-rod trap

A307 Grade A all-thread is sometimes supplied where a drawing calls for F1554 Grade 36 anchor rods. They are not interchangeable. A307 Grade A has no yield requirement, its elongation requirement applies only to machined specimens, and it has no reduction-of-area or impact requirement. A cert from a full-size A307 test will normally show only the breaking load and hardness. F1554 Grade 36 carries a 36 ksi minimum yield plus elongation and reduction-of-area minimums, and it offers optional Charpy supplementary requirements.

A307 Grade A: 60 ksi minimum tensile, no yield, 18 % elongation (machined specimens), no reduction of area, no impact
A307 Grade B: 60–100 ksi tensile, no yield, 18 % elongation (machined specimens), no reduction of area, no impact
F1554 Grade 36: 36 ksi minimum yield, a tensile range, elongation and reduction-of-area minimums, optional Charpy testing. See our ASTM F1554 guide for the current values

If the engineer of record specified F1554, test and certify to F1554. Charpy testing belongs to that F1554 context (see ASTM E23 and our impact testers); A307 itself has no impact test.

Chemical requirements

A307 limits four elements. Heat analysis comes from the steel producer; product analysis is a check on the finished fastener, so its limits are slightly wider. Maximum values:

Carbon: 0.29 % heat, 0.33 % product
Manganese: 1.20 % heat, 1.25 % product
Phosphorus: 0.04 % heat, 0.041 % product
Sulfur, Grade A: 0.15 % heat (resulfurized Grade A is not rejected on product sulfur)
Sulfur, Grade B: 0.05 % heat, 0.051 % product

Bismuth, selenium, tellurium and lead may not be intentionally added to Grade B heats. Chemical analysis follows ASTM A751. A36 bar is a common feedstock for A307 parts, but A307 does not require it; any steel that meets the table is acceptable.

The steel may come from open-hearth, basic-oxygen or electric-furnace melting. Heads may be hot- or cold-forged or machined from bar, and threads may be rolled or cut. Cold-headed non-hex fasteners with a head height of 0.5D or less must be stress-relieved at 875 °F (≈ 468 °C) or higher. For hex heads, stress relief is optional unless the purchaser requires it.

Mechanical requirements

Hardness

Grade A: 121–241 HB, or 69–100 HRB
Grade B: 121–212 HB, or 69–95 HRB

Bolts and studs shorter than three diameters (3D), and bolts with drilled or undersize heads, cannot be tension tested, so they are accepted on hardness alone and must fall inside both the minimum and maximum. For longer parts that pass the tension test, hardness acts mainly as a maximum; check the length rows in Table 2 of your copy of A307-21. Hardness may be taken anywhere on the surface or through the cross section. If hardness and tension results disagree, tension governs.

Full-size tensile loads (Table 3)

Full-size loads are based on the tensile stress area of the thread, As = 0.7854 × [D − 0.9743/n]², where D is the nominal diameter in inches and n is threads per inch. The minimum load for both grades is 60 ksi × As; the Grade B maximum is 100 ksi × As. Selected sizes (minimum for A and B / maximum for B):

¼-20 (As 0.0318 in²): 1,900 lbf (8.5 kN) / 3,180 lbf (14.1 kN)
½-13 (As 0.1419 in²): 8,500 lbf (37.8 kN) / 14,190 lbf (63.1 kN)
¾-10 (As 0.334 in²): 20,050 lbf (89.2 kN) / 33,400 lbf (148.6 kN)
1-8 (As 0.606 in²): 36,350 lbf (161.7 kN) / 60,600 lbf (269.6 kN)
1¼-7 (As 0.969 in²): 58,150 lbf (258.7 kN) / 96,900 lbf (431.0 kN)
1½-6 (As 1.405 in²): 84,300 lbf (375.0 kN) / 140,500 lbf (625.0 kN)
4-4 (As 11.08 in²): 664,800 lbf (2,957 kN) / 1,108,000 lbf (4,929 kN)

Note: The lbf values are from A307-21 Table 3; the kN values are our conversions (1 lbf = 4.448 N). Grade A has no upper limit, so a strong Grade A lot can break above the Grade B maximum.

Machined specimens (Table 4)

When a machined specimen is used, it must meet 60 ksi minimum tensile (Grade A), 60–100 ksi (Grade B), and 18 % minimum elongation in 2 in. for both grades. There is no yield value for either grade. For large diameters, F606 has long used a 0.500 in. round specimen with a 2 in. gauge length taken at mid-radius of the bolt; check the current F606/F606M edition for the exact location and the small-size rules. The tension procedure for the machined round is essentially the general metals method in ASTM E8.

The 18 % elongation applies only to machined specimens. Full-size bolts are judged on breaking load and fracture location, not elongation, which is why many A307 certs show no elongation at all.

Which test applies?

Shorter than 3D, or drilled or undersize head: hardness only, within both the minimum and maximum
1½ in. diameter and smaller, 3D or longer: full-size tension test is required
Over 1½ in.: full size is preferred; a machined specimen is allowed when machine capacity or part length makes full size impractical
Square or hex head bolts: wedge tension test
Round, countersunk and other head styles, studs and threaded rod: axial tension test (threaded rod is cut to length and tested like a stud)
Disagreement between methods: tension governs over hardness, and full-size governs over machined

A307 has no proof load test for bolts. The only proof-load language in the standard concerns the nuts. If a cert or a lab quote lists a bolt proof load for A307, it is borrowing from another specification.

How to run the A307 tensile test (per ASTM F606/F606M)

Note: The F606 details below (wedge angles, wedge hardness, exposed threads, speed) are values F606 has carried for many editions. F606/F606M-26 is current, so confirm them against your copy before writing a procedure.

1. Identify the part. Read the head mark (307A or 307B), measure diameter and length, and confirm the head style. If the bolt is shorter than 3D or has a drilled or undersize head, stop: it is accepted on hardness, not tension.
2. Choose wedge or axial. Square and hex heads get the wedge test; every other head style, studs and threaded rod get axial tension.
3. Set up the wedge. F606 has long specified a 10° wedge for bolts through 1 in. and 6° above 1 in., with the wedge hardened (historically 45 HRC minimum) and the hole clearance taken from the F606 table for the bolt size. Place the wedge directly under the head and orient the head so a flat, not a corner, carries the bearing load on the slope.
4. Engage the threads. Run the threaded end into a nut or threaded grip insert with full engagement, and leave at least six complete threads exposed between the bearing faces. For studs and rod, thread both ends into inserts with six threads exposed at each end.
5. Align and preload lightly. Take up slack so the bolt is seated on the wedge and centered in the load train.
6. Set the speed. F606 limits the free-running crosshead speed (historically 1 in./min, ≈ 25 mm/min); check the current edition. Use the same rate for every lot so results compare.
7. Load to fracture. Record the maximum load, not just “passed 20,050 lbf.” Grade B needs the peak value to show it stayed under 100 ksi × As.
8. Check the fracture. Fracture must be in the threads or the body. A break at the head-to-body junction is a failure at any load. Thread stripping in the nut or insert is not a valid result; retest with full engagement.
9. Judge pass/fail. Both grades must meet the Table 3 minimum; Grade B must also stay at or below the Table 3 maximum.
10. Report. Grade, size, length, head style, test type and wedge angle, maximum load (lbf and kN), fracture location, and the A307 and F606 editions used.

Worked example: ¾-10 Grade B hex bolt

Start with the stress area for D = 0.750 in. and n = 10 threads per inch:

0.9743 ÷ 10 = 0.09743
0.750 − 0.09743 = 0.65257 in.
0.65257² = 0.42585
As = 0.7854 × 0.42585 = 0.3345 in² (Table 3 rounds to 0.334 in²)
Minimum load = 60,000 psi × 0.334 in² = 20,040 lbf, listed in Table 3 as 20,050 lbf (89.2 kN)
Grade B maximum = 100,000 psi × 0.334 in² = 33,400 lbf (148.6 kN)

Result 1 (pass): the bolt breaks in the threads at 26,800 lbf (119.2 kN). That is 26,800 ÷ 0.334 = 80,240 psi, about 80 ksi, between 60 and 100 ksi. It passes as Grade B (and would pass as Grade A).

Result 2 (fail, over-strength): a bolt from another lot breaks in the threads at 34,500 lbf (153.5 kN), which is 103.3 ksi. That exceeds the Grade B maximum, so the lot is rejected as Grade B even though it is a perfectly good Grade A result.

Result 3 (fail, location): a bolt breaks at the head-to-shank fillet at 22,000 lbf. The load is above the minimum, but a head-junction fracture is a failure regardless of load.

The same arithmetic works for any size in the scope. For a 2-4½ bolt: 2.000 − 0.9743/4.5 = 1.7835 in., squared is 3.1808, times 0.7854 gives As ≈ 2.50 in², so the minimum is about 150,000 lbf (667 kN) and the Grade B maximum about 250,000 lbf (1,112 kN).

Choosing the test machine and grips

The most common sizing mistake is choosing a machine from the Table 3 minimum loads. A bolt does not stop at its minimum. Grade B is allowed to reach 100 ksi × As, and Grade A has no upper limit at all (its 100 HRB hardness cap keeps it in roughly the same range). Size the frame, load cell and grips for the Grade B maximum and leave some headroom, so a strong lot does not run the machine out of capacity before the bolt breaks.

¼–½ in.: highest Grade B load about 63 kN (14,190 lbf). A 100 kN benchtop frame with 100 kN bolt grips covers it.
¾ in.: up to about 149 kN (33,400 lbf). Use a 250 kN class floor-standing frame; a 100 kN grip set is too small for full-strength Grade B.
1 in.: up to about 270 kN (60,600 lbf). A 250 kN frame cannot break a full-strength 1 in. Grade B bolt; a 600 kN frame with grips rated around 300 kN can.
1¼ in.: up to about 431 kN (96,900 lbf). A 600 kN frame.
1½ in.: minimum 375 kN, maximum about 625 kN (140,500 lbf). A 600 kN frame is too small for the full range; use a 1,000 kN frame. This is the largest size where full-size testing is mandatory.
Over 1½ in.: a full-size 2 in. bolt can reach about 1,112 kN, which a 2,000 kN frame handles. A 4 in. bolt needs nearly 3,000 kN just to reach the minimum, so large diameters are usually tested with a machined 0.500 in. round (about 87 kN at 100 ksi).

Our Galdabini floor-standing universal testing machines run from 250 kN up to 2,000 kN, which covers every mandatory full-size A307 test and full-size work well beyond 1½ in. The videos on this page show our bolt grips set up for A307 and general bolt testing.

Bolt grips for wedge and axial tension

Our bolt grips hold the bolt head on a ledge and take the threaded end in a threaded insert, so changing sizes means swapping inserts rather than rebuilding the load train. For hex and square heads, a hardened wedge washer sits under the head to apply the F606 wedge angle; tell us the bolt sizes and wedge angles you need when you ask for a quote. Rate the grips above the Grade B maximum for your largest size, not the Table 3 minimum. The full wedge and axial procedures are covered in our ASTM F606 guide.

Studs, threaded rod and machined specimens

Studs and threaded rod are tested axially with threaded inserts on both ends. For machined round specimens and plain-end bar, wedge grips with Vee jaws hold the specimen securely, and hydraulic grips make sense for large rod and high-volume work, where consistent clamping force and quick loading save time.

Measuring elongation

The 18 % elongation on machined specimens is normally measured from gauge marks after fracture. If you also want a stress-strain curve, a 2 in. gauge clip-on unit from our extensometers range fits the 0.500 in. round; check the model's recommended removal point before fracture.

Threads, dimensions and galvanizing

Unless otherwise specified, threads are UNC Class 2A per ASME B1.1, bolt dimensions follow ASME B18.2.1, and threaded rod follows ASME B18.31.3. Grade A bolts are hex-head; Grade B bolts are heavy hex.

Zinc coating is either hot-dip per F2329/F2329M or mechanically deposited per B695 Class 55. If the order does not say which, the supplier chooses, but the bolts and nuts in a lot must use the same process. Mixing hot-dip bolts with mechanically galvanized nuts is not allowed.

Zinc-coated threads may exceed the Class 2A maximum by an allowance that runs from 0.016 in. on small sizes to 0.050 in. on 1¾–4 in., and the nuts are overtapped to match. In a dispute, fit is checked with an oversize nut or a Class X ring gauge that must assemble by hand with light oil.

This affects testing. A standard Class 2B threaded insert will not run onto a hot-dip bolt, and an overtapped nut on an uncoated bolt has less thread engagement and can strip before the bolt breaks. Use inserts or nuts tapped to suit the coated thread, and never record a stripped thread as a bolt result.

Sampling, certification and marking

A307 assumes continuous production with the manufacturer's own sample inspections, so shipment-by-shipment testing is not normally required. A certified test report showing the last completed mechanical tests is supplied when the purchase order asks for it. If extra testing is ordered, a lot is the same product type, nominal size and nominal length.

If a sample fails, the retest is double the original sample from the same lot, and every piece must pass. A machined specimen with a machining defect may be discarded and replaced. Nonconforming product is handled per ASTM F1470, and surface discontinuities are judged per ASTM F788.

The order should state the designation and year (A307-21), product and head style, grade (Grade A is furnished if none is stated), quantity, size and length, coating process, washers if needed (they are ordered separately), and whether a certified test report or extra testing is required.

Marking

Bolt heads, and one end of each stud, carry the manufacturer's or private-label identification plus the grade mark 307A or 307B, raised or depressed on the top of the head. Threaded rod is marked per ASME B18.31.3, and end marking is optional. Shipping units are labeled with the designation and grade, size, manufacturer, quantity, purchase order number if specified, and country of origin.

Matching nuts and washers

The default nut is ASTM A563 Grade A. Grade A bolts take hex nuts in the smaller sizes and heavy hex nuts in the larger sizes; Grade B bolts take heavy hex nuts in all sizes. Check A307-21 §1 for the size where Grade A switches from hex to heavy hex. Nuts with a higher proof load stress are also acceptable. Washers, such as ASTM F436, are not required by A307 and are ordered separately.

Common mistakes and failure modes

Ignoring the Grade B ceiling. Recording only “passed minimum” hides over-strength Grade B, which is a rejection. Always record peak load.
Sizing the machine on Table 3 minimums. A 1½ in. Grade B bolt can legitimately reach 625 kN; a 250 kN or 300 kN frame will not break it.
Axial-testing hex-head bolts. The wedge test is required because it adds head bending and checks the head-to-shank fillet. Skipping the wedge removes the most important check.
Wrong wedge angle. Using a 6° wedge on a ¾ in. bolt, or a 10° wedge on a 1¼ in. bolt, makes the test easier or harder than F606 intends.
Too few exposed threads. A short free thread length constrains the thread and raises the apparent breaking load. Keep at least six complete threads between bearing faces.
Tension testing parts shorter than 3D. They are exempt and accepted on hardness; a tension result on a stubby bolt is not meaningful.
Accepting a head-junction fracture because the load was high. It is a failure at any load.
Thread stripping recorded as a break. Usually a worn insert, a mismatched coated thread or short engagement. Fix the setup and retest.
Reporting yield, reduction of area or Charpy for A307. None are required for Grades A or B; they belong to F1554 or other specifications.
Citing A370 instead of F606. ASTM A370 Annex A3 is the general steel-fastener annex, but A307 itself calls up F606/F606M.
Treating A307 Grade A as F1554 Grade 36. The anchor-rod specification adds yield, ductility and optional toughness requirements that A307 product has never been tested for.
Using outdated grade charts. Any chart that lists an active Grade C predates 2007.

A307 vs related standards

ASTM F606/F606M: the test methods A307 calls up for hardness, wedge tension, axial tension and machined specimens.
ASTM A370: the general steel mechanical-testing standard. Annex A3 covers steel fasteners in general; A307 points to F606 instead.
ASTM F1554: anchor rods in Grades 36, 55 and 105. Grade 36 replaced A307 Grade C and adds yield, elongation and reduction-of-area requirements plus optional Charpy tests.
ASTM F3125/F3125M: structural bolts. Since 2015 it covers the former A325 and A490 specifications, plus F1852 and F2280, as grades. These are much stronger quenched-and-tempered bolts with proof-load requirements.
ASTM A449 and A354: quenched-and-tempered bolts and studs for higher-strength general use.
ASTM A563 and F436: nuts and hardened washers. A563 Grade A is the default nut for A307; washers are ordered separately.
SAE J429 Grade 2: a similar low-carbon bolt for automotive and general use. It is not interchangeable with A307 because J429 has its own proof-load and yield requirements.
ISO 898-1 property class 4.6: often cited as the nearest metric analogue, but it is not equivalent. There is no ISO counterpart to A307.
ASTM E8: the general metals tension method, relevant to machined specimens. See our E8 guide.

Equipment from Universal Grip for A307 testing

We design and build grips and fixtures in Massachusetts and supply Galdabini universal testing machines, so we can quote the whole A307 load train: frame, load cell, grips, wedge washers and inserts.

Bolt grips: head-rest grips with threaded inserts and hardened wedge washers for F606 wedge and axial tension, in 100 kN and 300 kN classes and larger on request.
Wedge grips: Vee-jaw grips for machined rounds and plain-end bar.
Hydraulic grips: for large threaded rod, bar and high-throughput labs.
Floor-standing universal testing machines: Galdabini frames from 250 kN to 2,000 kN; 1,000 kN covers every mandatory full-size A307 test.
Extensometers: clip-on and non-contact options for machined-specimen elongation.
Impact testers: pendulum Charpy testers for labs that also certify F1554 anchor rods to the supplementary impact requirements.

Send us your bolt sizes, grades, head styles and annual volume, and we will recommend a frame capacity and grip set sized to the real breaking loads. Request a quote.

ASTM A307 FAQ

What is ASTM A307?

ASTM A307 is the standard specification for carbon steel bolts, studs and threaded rod with a 60,000 psi minimum tensile strength, in diameters from ¼ in. through 4 in. The current edition is A307-21. It covers Grade A for general use and Grade B for cast-iron flanged piping joints, and it sets chemistry, hardness, full-size breaking loads, threads and marking. Test methods come from ASTM F606/F606M.

What is the difference between A307 Grade A and Grade B?

Grade A is general-purpose with a 60 ksi minimum tensile strength and no upper limit, supplied with hex heads. Grade B is for flanged piping joints with cast-iron flanges. It has a 60–100 ksi tensile range, heavy hex heads, a tighter sulfur limit of 0.05 % and a lower hardness cap of 95 HRB. The 100 ksi maximum keeps an over-strong bolt from overloading brittle flanges.

Is A307 Grade C still available?

No. Grade C, which covered anchor bolts with a 36 ksi minimum yield, was removed from A307 in 2007 and replaced by ASTM F1554 Grade 36. F1554 adds yield, elongation and reduction-of-area requirements and optional Charpy impact testing. Supplier charts that still list an active Grade C are out of date. Older Grade C anchor bolts were marked with a green-painted end.

What is the yield strength of A307 bolts?

A307 Grades A and B have no minimum yield strength requirement, so most certs show none. Only tensile strength, hardness and, for machined specimens, elongation are specified. Values like “36 ksi yield” quoted online come from the retired Grade C. If your design needs a guaranteed yield strength, specify ASTM F1554 Grade 36 or a higher-strength bolt such as A449.

What is the hardness of A307 bolts?

Grade A bolts must be 121–241 HB (69–100 HRB) and Grade B bolts 121–212 HB (69–95 HRB). Bolts shorter than three diameters, or with drilled or undersize heads, are accepted on hardness alone and must meet both limits. Longer bolts are accepted on the tension test, with hardness acting mainly as a maximum. When hardness and tension disagree, the tension result governs.

How is an A307 bolt tensile tested?

A307 bolts are tested per ASTM F606/F606M. Square and hex head bolts get a wedge tension test, with F606 traditionally using a 10° wedge through 1 in. and 6° above. Other head styles, studs and threaded rod get axial tension. Bolts up to 1½ in. must be tested full size, and the fracture must occur in the threads or body, never at the head-to-shank junction.

What is the minimum breaking load of a ¾ in. A307 bolt?

A ¾-10 A307 bolt has a tensile stress area of 0.334 in², so its minimum full-size breaking load is 20,050 lbf (about 89 kN) for both Grade A and Grade B. A Grade B bolt must also break at no more than 33,400 lbf (about 149 kN), which equals 100 ksi on the stress area. Grade A has no maximum breaking load.

Is A307 the same as SAE Grade 2?

No. A307 and SAE J429 Grade 2 are both low-carbon steel bolts in a similar strength range, but they are written by different bodies with different requirements. J429 includes proof-load and yield requirements that A307 Grades A and B do not have, and the marking, sampling and test rules differ. Do not substitute one for the other without the engineer's approval.

Can A307 bolts be used as anchor bolts?

Only if the engineer of record allows it. Anchor rods are normally specified to ASTM F1554, and the former A307 Grade C anchor bolt was replaced by F1554 Grade 36 in 2007. A307 Grade A has no yield, reduction-of-area or impact requirements, and full-size test certs usually show only breaking load and hardness, so it cannot be certified as F1554 product.

What nut goes with an A307 bolt?

The default nut is ASTM A563 Grade A. Grade A bolts use hex nuts in the smaller sizes and heavy hex nuts in the larger sizes, while Grade B bolts use heavy hex nuts in every size. A nut with a higher proof load stress is also acceptable. For zinc-coated bolts, the nut must be overtapped to suit the coating and galvanized by the same process.

Can A307 bolts be hot-dip galvanized?

Yes. A307 allows hot-dip zinc coating per ASTM F2329/F2329M or mechanically deposited zinc per B695 Class 55. Bolts and nuts in a lot must use the same process. Coated threads may exceed the Class 2A maximum by 0.016 in. on small sizes up to 0.050 in. on large sizes, and nuts are overtapped to match. Use suitably tapped inserts when testing coated bolts.

What size testing machine do I need for A307 bolts?

Size the machine for the Grade B maximum, not the minimum. Up to ½ in. needs about 63 kN, ¾ in. about 149 kN, 1 in. about 270 kN and 1½ in. about 625 kN. A 1,000 kN frame covers every size where full-size testing is mandatory. Larger diameters are often tested with machined 0.500 in. round specimens, which need under 100 kN.

Literature

Pricing and Availability

ASTM A307 Carbon Steel Bolt and Rod Tensile Test