GOST R ISO 7050-2012 Self-tapping Screws

SELF-TAPPING SCREWS WITH COUNTERSUNK HEAD AND CROSS RECESS

Cross-recessed countersunk (flat) head tapping screws

Effective date: 2014-01-01

1 Scope

This standard establishes the characteristics of self-tapping screws with countersunk head and cross recess with thread sizes from ST2.2 to ST9.5 inclusive.

2 Normative references

The following normative documents are required for the application of this standard. For dated references, only the cited edition applies. For undated references, the latest edition of the referenced standard (including any amendments) applies.

ISO 225 Fasteners. Bolts, screws, studs and nuts. Symbols and designations of dimensions (ISO 225, Fasteners — Bolts, screws, studs and nuts — Symbols and designations of dimensions)

ISO 1478 Tapping screw thread (ISO 1478, Tapping screws thread)

ISO 2702 Heat-treated steel tapping screws. Mechanical properties (ISO 2702, Heat-treated steel tapping screws — Mechanical properties)

ISO 3269 Fasteners. Acceptance inspection (ISO 3269, Fasteners — Acceptance inspection)

ISO 3506-4 Mechanical properties of corrosion-resistant stainless steel fasteners. Part 4. Tapping screws (ISO 3506-4, Mechanical properties of corrosion-resistant stainless steel fasteners — Part 4: Tapping screws)

ISO 4042 Fasteners. Electroplated coatings (ISO 4042, Fasteners — Electroplated coatings)

ISO 4757 Cross recesses for screws (ISO 4757, Cross recesses for screws)

ISO 4759-1 Tolerances for fasteners. Part 1. Bolts, screws, studs and nuts. Product grades A, B and C (ISO 4759-1, Tolerances for fasteners — Part 1: Bolts, screws, studs and nuts — Product grades A, B and C)

ISO 7721 Countersunk head screws. Head configuration and gauging (ISO 7721, Countersunk head screws — Head configuration and gauging)

ISO 7721-2 Countersunk head screws. Part 2. Penetration depth of cross recesses (ISO 7721-2, Countersunk flat head screws — Part 2: Penetration depth of cross recesses)

ISO 8992 Fasteners. General requirements for bolts, screws, studs and nuts (ISO 8992, Fasteners — General requirements for bolts, screws, studs and nuts)

ISO 10683 Fasteners. Non-electrolytically applied zinc flake coatings (ISO 10683, Fasteners — Non-electrolytically applied zinc flake coatings)

ISO 16048 Passivation of corrosion-resistant stainless steel fasteners (ISO 16048, Passivation of corrosion-resistant stainless-steel fasteners)

3 Dimensions

Screw dimensions are shown in Figure 1 and Table 1. Dimension symbols and designations are in accordance with ISO 225.

Table 1 — Dimensions

Thread d								ST2.2	ST 2.9	ST 3.5	ST 4.2	ST4.6	ST 5.5	ST 6.3	ST8	ST 9.S
P*								0.8	1.1	1.3	1.4	1.6	1.6	1.8	2.1	2.1
P1)		max						1.6	2.2	2.6	2.6	3.2	3.6	3.6	4.2	4.2
a2)		Theoretical				max		4.4	6.3	8.2	9.4	10.4	11.5	12.6	17.3	20.0
		Actual				max		3.8	5.S	7.3	8.4	9.3	10.3	11.3	15.8	18.3
						min		3.5	5.2	6.9	8.0	8.9	9.9	10.9	15.4	17.8
k		max						1.10	1.70	2.35	2.60	2.80	3.00	3.15	4.65	5.25
r		max						0.8	1.2	1.4	1.6	2.0	2.2	2.4	3.2	4.0
Cross recess		Recess size						0	1	2			3		4
		Type H		m		max		1.0	3.2	4.4	4.6	5.2	6.6	6.8	8.9	10.0
				Gauge penetration depth		max		1.2	2.1	2.4	2.6	3.2	3.3	3.S	4.6	5.7
						min		0.9	1.7	1.9	2.1	2.7	2.6	3.0	4.0	5.1
		Type Z		m		max		2.0	3.0	4.1	4.4	4.9	6.3	6.6	8.8	9.8
				Gauge penetration depth		max		1.20	2.01	2.20	2.S1	3.05	3.18	3.45	4.60	5.64
						min		0.95	1.76	1.75	2.06	2.60	2.73	3.00	4.15	5.19
y 3)		Type C						2.0	2.6	3.2	3.7	4.3	5.0	6.0	7.5	6.0
		Type F						1.6	2.1	2.5	2.6	3.2	3.6	3.6	4.2	4.2
		Type R						—	—	2.7	3.2	3.6	4.3	5.0	6.3	—
Thread								l
Type C and Type R					Type F
nom.	min		max		min		max		—	—	—	—	—	—	—	—
4.5	3.7		S.3		3.7		4.5				—	—	—	—	—	—
6.6	6.7		7.3		6.7		6.6						—	—	—	—
9.6	8.7		10.3		8.7		9.5								—	—
13	12.2		13.6		12.2		13.0		Scope
16	(6.2		16.8		(6.2		16.0
19	(8.2		19.8		18.2		19.0
22	22.2		22.8		20.7		22.0
26	24.2		25.8		23.7		26.0
32	30.7		33.3		30.7		32.0
36	36.7		39.3		36.7		38.0
46	43.7		46.3		43.6		46.0
60	46.7		61.3		48.5		50.0

Table 2

Material		Steel, in accordance with ISO 2702	Corrosion-resistant steel
General requirements		ISO 8992
Thread		ISO 1478
Cross recess		ISO 4757. ISO 7721-2
Mechanical properties	Steel grade/hardness	—	A2-20H. A4-20H. A5-20H
	Standard designation	ISO 2702	ISO 3506-4
Tolerance	Product grade	A
	Standard designation	ISO 4759-1
Finish — coating		Plain/per requirements for electroplated coatings per ISO 4042. Requirements for non-electrolytically applied zinc flake coatings per ISO 10683. Additional requirements, other finish or other coatings shall be agreed between the supplier and the purchaser	Coatings Passivation requirements per ISO 16048
Acceptance		Acceptance inspection per ISO 3269

Corresponds to ISO 7050.