Engineering quick reference

IQ-CAL-010REV 0NOT A CERTIFICATE

IQEG CALCULATION LAB

Engineering quick-reference desk

IQ-CAL-010 · Rev 0 Indicative · 11/11/2026 · Not a certificate

INPUTS + RESULTSUNITS AS TABULATED

IQ Engineering Group · Sydney · IQ-CAL-010 · Engineering quick-reference desk · millimetres, kN, kNm, MPa unless noted

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FIND · hole M20 Nti stair H7 key 9550

7 tables in Bolts + fasteners. LOAD EXAMPLE searches M20 across the desk. Where a topic has more than one standard, pick it on the card.

AS 1275 · ISO 898-1 · ISO 4014/4017#bolt-dims

Metric coarse bolts — d, pitch, As, An, tap, AF

Size	d mm	p mm	As mm²	An mm²	Tap	AF
M6	6	1	20.1	28.3	5	10
M8	8	1.25	36.6	50.3	6.8	13
M10	10	1.5	58	78.5	8.5	16
M12	12	1.75	84.3	113.1	10.2	18
M16	16	2	157	201.1	14	24
M20	20	2.5	245	314.2	17.5	30
M24	24	3	353	452.4	21	36
M27	27	3	459	572.6	24	41
M30	30	3.5	561	706.9	26.5	46
M36	36	4	817	1017.9	32	55

Australian / ISO metric coarse. Structural 8.8 is this thread.

M20: d 20, p 2.5, As 245 mm², An 314 mm², tap 17.5, AF 30.
Use As whenever threads are in the shear plane — the usual conservative assumption.
Spanner AF is across-flats of the hex. A 30 mm socket on M20; 36 mm on M24.

AS 4100 Table 14.3.5#holes

Bolt holes — standard, oversize, short slot, long slot

Bolt	Standard dh	Oversize	Short slot	Long slot
M12	14	16	14 × 18	14 × 30
M16	18	20	18 × 22	18 × 40
M20	22	24	22 × 26	22 × 50
M24	26	30	26 × 32	26 × 60
M30	33	36	33 × 40	33 × 75
M36	39	42	39 × 46	39 × 90

kh = 1.00 standard, 0.85 oversize/short slot, 0.70 long slot. Use standard holes in the direction of force where possible.

M20 standard hole is 22 mm. Oversize 24 mm. Short slot 22 × 26. Long slot 22 × 50.
kh reduces friction capacity: 1.00 / 0.85 / 0.70. Do not mix hole types in the direction of force without checking kh.
A slotted hole is for erection, not for sliding in service unless the connection is designed as a slotted joint.

AS 4100 cl. 9.6 / 14.3.5 · IQ-CAL-009#edge-pitch

Edge distance and pitch — practical minima

Bolt	e rolled	e sawn / flame	e sheared	p min	p preferred
M12	15	20	25	30	45
M16	20	25	30	40	60
M20	25	30	35	50	70
M24	30	40	45	60	90
M30	40	45	55	75	100
M36	45	55	65	90	100

Values in mm, hole centre to edge. p max ≈ 15t (compression) or 32t (tension), capped. Gauge lines on UB/UC: see bolt-spacing tool.

M20: 25 mm to a rolled edge, 30 mm sawn, 35 mm sheared. Preferred pitch 70 mm, minimum 50 mm.
Gauge on a 310UB flange is typically 90 mm. Check IQ-CAL-009 before punching.
End distance along a member is not the same as edge distance to a rolled flange — use the matching row.

ISO 7089 · AS 1237.1#washers

Plain washers ISO 7089 (200 HV)

Bolt	ID ≈ mm	OD mm	t mm
M6	6.4	12	1.6
M8	8.4	16	1.6
M10	10.5	20	2
M12	13	24	2.5
M16	17	30	3
M20	21	37	3
M24	25	44	4
M27	28	50	4
M30	31	56	4
M36	37	66	5

Structural assemblies: use the washer specified with the bolt set (AS/NZS 1252.1). Do not substitute a thin commercial washer under a tensioned head.

ISO 898-1:2013#proof

ISO proof load Fp and min tensile Fm — class 8.8 / 10.9

Size	8.8 Fp kN	8.8 Fm kN	10.9 Fp kN	10.9 Fm kN
M12	48.9	67.4	70	87.7
M16	91	125.6	130.3	163.3
M20	147	203.4	203.4	254.8
M24	211.8	293	293	367.1
M27	275.4	381	381	477.4
M30	336.6	465.6	465.6	583.4
M36	490.2	678.1	678.1	849.7

Fp = Sp As, Fm = Rm As. 8.8: Sp 580 MPa (d≤16) / 600 (d>16), Rm 800/830. 10.9: Sp 830, Rm 1040. Snug commercial work is often 65% of proof — not Nti.

AS 4100 Table 15.2.5.1#nti

AS 4100 specified pretension Nti

Size	8.8 kN	10.9 kN
M16	95	130
M20	145	190
M24	210	270
M30	335	445
M36	490	650

M12 is not a pretensioned structural size in this table. Part-turn and DTI are the methods; torque is not a substitute unless a qualified k-factor procedure is used.

M20 8.8 Nti = 145 kN. M24 8.8 Nti = 210 kN. M20 10.9 Nti = 190 kN.
TF / TB connections use Nti in the slip check. Snug 8.8/S does not.
Torque is a site convenience, not the Standard method. Use IQ-CAL-008 if a k-factor procedure is specified.

AS 4100 cl. 9.2 · AS 3990#phi-bolts

Bolt design — AS 4100 φ and AS 3990 allowables

Quantity	AS 4100	AS 3990 (WSD)
φ bolts	0.80	— (allowable)
Tension	φ Ntf = 0.80 fu As	0.33 fu As
Shear, threads in plane	φ × 0.62 fu kr As ns	0.21 fu As ns
Shear, shank in plane	φ × 0.62 fu kr An ns	0.25 fu An ns
Combined N and V	(V/φVf)²+(N/φNtf)² ≤ 1	V/Vall + N/Nall ≤ 1.0 typical

kr = 1.0 for standard holes. Threads in the shear plane is the usual conservative assumption unless the grip is detailed otherwise.

Worked 8.8, ns=1, threads in, kr=1. φNtf = 0.80×830×As/1000. φVf = 0.80×0.62×830×As/1000. AS 3990 Nall = 0.33 fu As, Vall = 0.21 fu As.
M20 8.8: φNtf 162.7 kN, φVf 100.9 kN. AS 3990 Nall 67.1, Vall 42.7. 4100 is about 2.4× the 3990 allowable in tension.
Do not mix φ from AS 4100 with AS 3990 allowables in the same check. Existing plant is often still on 3990 (WSD).

CALCULATE · size, grade, standard

SIZE

GRADE

STANDARD

THREADS

Size	As mm²	φNtf 4100	φVf 4100	Nall 3990	Vall 3990
M12	84.3	56.0	34.7	23.1	14.7
M16	157.0	104.2	64.6	43.0	27.4
M20	245.0	162.7	100.9	67.1	42.7
M24	353.0	234.4	145.3	96.7	61.5
M27	459.0	304.8	189.0	125.7	80.0
M30	561.0	372.5	231.0	153.7	97.8
M36	817.0	542.5	336.3	223.8	142.4

M20 8.8 · fu 830 MPa · ns = 1 · threads IN (As). AS 4100 φNtf 162.7 kN · φVf 100.9 kN. AS 3990 Nall 67.1 kN · Vall 42.7 kN. kN. φ = 0.80. kr = 1. Do not mix φ with 3990 allowables in the same check.

Bolt	e rolled	e sawn / flame	e sheared	p min	p preferred
M12	15	20	25	30	45
M16	20	25	30	40	60
M20	25	30	35	50	70
M24	30	40	45	60	90
M30	40	45	55	75	100
M36	45	55	65	90	100

Bolt	e rolled	e sawn / flame	e sheared	p min	p preferred
M12	15	20	25	30	45
M16	20	25	30	40	60
M20	25	30	35	50	70
M24	30	40	45	60	90
M30	40	45	55	75	100
M36	45	55	65	90	100

Bolt	e rolled	e sawn / flame	e sheared	p min	p preferred
M12	15	20	25	30	45
M16	20	25	30	40	60
M20	25	30	35	50	70
M24	30	40	45	60	90
M30	40	45	55	75	100
M36	45	55	65	90	100