Standard No.:	GB/T 4436-2026
English Name:	Tolerances on form and dimensions of wrought aluminium and aluminium alloy tubes
Chinese Name:	铝及铝合金管材外形尺寸及允许偏差
Chinese Classification:	H61    Light metals and their alloys
Professional Classification:	GB    National Standard
ICS Classification:	77.150.10 77.150.10    Aluminium products 77.150.10
Source Content Issued by:	SAMR, SAC
Issued on:	2026-05-22
Implemented on:	2026-12-1
Status:	to be valid
Superseding:	GB/T 4436-2012 Wrought aluminum and aluminum alloy tubes—Dimensions and deviations
Target Language:	English
File Format:	PDF
Word Count:	20500 words
Translation Price(USD):	615.0
Delivery:	via email in 1~8 business day

GB/T 4436-2026 Tolerances on form and dimensions of wrought aluminium and aluminium alloy tubes English, Anglais, Englisch, Inglés, えいご This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered. ICS CCS National Standard of the People's Republic of China ‌GB/T 4436-2026 Tolerances on form and dimensions of wrought aluminium and aluminium alloy tubes 铝及铝合金管材外形尺寸及允许偏差 Issue date: 2026-01-28 Implementation date: 2027-02-01 Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China the Standardization Administration of the People's Republic of China Contents Foreword 1 Scope 2 Normative references 3 Terms and definitions 4 Dimensions and specifications 5 Dimensional tolerances 6 Test methods Aluminium and aluminium alloy tubes — Dimensions and tolerances 1 Scope This document specifies the dimensions and tolerances of aluminium and aluminium alloy round tubes, square tubes, flat tubes, hexagonal tubes, octagonal tubes and elliptical tubes. This document is applicable to hot-extruded seamless round tubes and welded round tubes, square tubes, flat tubes, hexagonal tubes and octagonal tubes of aluminium and aluminium alloys, cold-rolled or cold-drawn welded or seamless round tubes, and cold-drawn welded or seamless square tubes, flat tubes and elliptical tubes. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies. GB/T 8170, Rules of rounding off for numerical values and expression and judgement of limiting values 3 Terms and definitions No terms and definitions are required to be defined in this document. 4 Dimensions and specifications 4.1 Typical cross-sectional dimensions and specifications for extruded seamless round tubes are given in Table 1. 4.2 Cross-sectional dimensions and specifications for extruded welded round tubes, flat tubes, square tubes, hexagonal tubes and octagonal tubes shall be determined by agreement between the supplier and the purchaser and stated in the order. 4.3 Typical cross-sectional dimensions and specifications for cold-drawn or cold-rolled welded or seamless round tubes are given in Table 2. 4.4 Typical cross-sectional dimensions and specifications for cold-drawn welded or seamless square tubes are given in Table 3. 4.5 Typical cross-sectional dimensions and specifications for cold-drawn welded or seamless flat tubes are given in Table 4. 4.6 Typical cross-sectional dimensions and specifications for cold-drawn welded or seamless elliptical tubes are given in Table 5. 5 Dimensional tolerances 5.1 Extruded seamless round tubes 5.1.1 Outside diameter 5.1.1.1 When the tube wall thickness is greater than 2.5 % of the outside diameter, the outside diameter tolerances for extruded seamless round tubes shall comply with Table 6. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. 5.1.1.2 When the tube wall thickness is not greater than 2.5 % of the outside diameter, the outside diameter tolerances for extruded seamless round tubes shall comply with the following requirements: a) When the wall thickness to outside diameter ratio is > 0.5 % to 1.0 %, the permissible tolerance shall be 4 times the corresponding value in Table 6; b) When the wall thickness to outside diameter ratio is > 1.0 % to 1.5 %, the permissible tolerance shall be 3 times the corresponding value in Table 6; c) When the wall thickness to outside diameter ratio is > 1.5 % to 2.0 %, the permissible tolerance shall be 2 times the corresponding value in Table 6; d) When the wall thickness to outside diameter ratio is > 2.0 % to 2.5 %, the permissible tolerance shall be 1.5 times the corresponding value in Table 6. 5.1.2 Wall thickness The wall thickness tolerances for extruded seamless round tubes shall comply with Table 7. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. 5.1.3 Straightness Except for the O temper, the straightness of extruded seamless round tubes shall comply with Table 8. When the purchaser requires the high-precision grade or extra-high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. When the purchaser has special requirements for the straightness of O-temper extruded seamless round tubes or for other tempers, the requirements shall be determined by agreement between the supplier and the purchaser and stated in the order. 5.1.4 Length 5.1.4.1 The length of extruded seamless round tubes supplied in random lengths shall be not less than 300 mm. 5.1.4.2 The length tolerances for extruded seamless round tubes supplied in fixed lengths (or multiple fixed lengths) shall comply with Table 9. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. For tubes supplied in multiple fixed lengths, each saw cut should preferably have a sawing allowance of 5 mm. 5.1.5 Squareness of cut The squareness of cut for extruded seamless round tubes shall comply with Table 10. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. 5.2 Extruded welded round tubes 5.2.1 Outside diameter 5.2.1.1 When the tube wall thickness is greater than 2.5 % of the outside diameter, the outside diameter tolerances for extruded welded round tubes shall comply with Table 11. 5.2.1.2 When the tube wall thickness is not greater than 2.5 % of the outside diameter, the outside diameter tolerances for extruded welded round tubes shall comply with the following requirements: a) When the wall thickness to outside diameter ratio is > 0.5 % to 1.0 %, the permissible tolerance shall be 4 times the corresponding value in Table 11; b) When the wall thickness to outside diameter ratio is > 1.0 % to 1.5 %, the permissible tolerance shall be 3 times the corresponding value in Table 11; c) When the wall thickness to outside diameter ratio is > 1.5 % to 2.0 %, the permissible tolerance shall be 2 times the corresponding value in Table 11; d) When the wall thickness to outside diameter ratio is > 2.0 % to 2.5 %, the permissible tolerance shall be 1.5 times the corresponding value in Table 11. 5.2.2 Wall thickness The wall thickness tolerances for extruded welded round tubes shall comply with Table 12. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. 5.2.3 Straightness The straightness of extruded welded round tubes with wall thickness not less than 1.5 % of the outside diameter shall comply with Table 13. When the purchaser requires straightness for extruded welded round tubes with wall thickness less than 1.5 % of the outside diameter or has special requirements for straightness, the requirements shall be determined by agreement between the supplier and the purchaser and stated in the order. 5.2.4 Length 5.2.4.1 The length of extruded welded round tubes supplied in random lengths shall be not less than 300 mm. 5.2.4.2 The length tolerances for extruded welded round tubes supplied in fixed lengths (or multiple fixed lengths) shall comply with Table 14. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. For tubes supplied in multiple fixed lengths, each saw cut should preferably have a sawing allowance of 5 mm. 5.2.5 Squareness of cut The squareness of cut for extruded welded round tubes shall comply with Table 15. When the purchaser requires the high-precision grade, it shall be stated in the order. If not stated, the ordinary grade shall be supplied. 5.3 Extruded welded square tubes, flat tubes, hexagonal tubes and octagonal tubes 5.3.1 Side length (or distance between opposite faces) 5.3.1.1 Except for tubes in the O and T×510 tempers, when the tube wall thickness is greater than 2.5 % of the maximum distance between opposite faces, the side length (or distance between opposite faces) tolerances for extruded welded square tubes, flat tubes, hexagonal tubes and octagonal tubes shall comply with Table 16. 5.3.1.2 Except for tubes in the O and T×510 tempers, when the tube wall thickness is not greater than 2.5 % of the maximum distance between opposite faces, the side length (or distance between opposite faces) tolerances for extruded welded square tubes, flat tubes, hexagonal tubes and octagonal tubes shall comply with the following requirements: a) When the wall thickness to maximum distance between opposite faces ratio is > 0.5 % to 1.0 %, the permissible tolerance shall be 4 times the corresponding value in Table 16; b) When the wall thickness to maximum distance between opposite faces ratio is > 1.0 % to 1.5 %, the permissible tolerance shall be 3 times the corresponding value in Table 16; c) When the wall thickness to maximum distance between opposite faces ratio is > 1.5 % to 2.0 %, the permissible tolerance shall be 2 times the corresponding value in Table 16; d) When the wall thickness to maximum distance between opposite faces ratio is > 2.0 % to 2.5 %, the permissible tolerance shall be 1.5 times the corresponding value in Table 16. 5.3.1.3 The side length (or distance between opposite faces) tolerances for extruded welded square tubes, flat tubes, hexagonal tubes and octagonal tubes in the O and T×510 tempers shall be determined by agreement between the supplier and the purchaser and stated in the order. 5.3.2 Wall thickness