1. What BS Standards Are

BS (British Standards) are issued by BSI (British Standards Institution).

• Types / prefixes

  • BS – purely British standard.

  • BS EN – British adoption of a European standard.

  • BS EN ISO / BS ISO – British adoption of ISO or ISO+EN standards.

• Status

  • Formally voluntary, but they become mandatory in practice when:

    • Cited in law or regulation, or

    • Written into contracts, specifications, drawings.

• Typical format

  • BS 1234:2019 (standard number + year).

BS standards are strongly integrated with the EN (European) and ISO systems.

2. What GB / GB/T Standards Are

GB standards are Chinese national standards, issued/approved by national standardization authorities.

• Categories

  • GB – mandatory national standard.

  • GB/T – recommended / voluntary national standard.

• In practice, a GB/T standard becomes effectively mandatory once it is:

  • Cited in laws / regulations, or

  • Written into contracts, tenders or drawings.

GB/GB-T standards are closely linked to Chinese regulations and industry practice.

3. System-Level Differences (BS vs GB / GB-T)

3.1 Standard System and Legal Role

• BS system

  • Managed by BSI, but many are BS EN or BS EN ISO, aligned with EU/ISO.

  • Often used to support CE / UKCA and European-style conformity.

• GB system

  • Managed as part of China’s national standardization framework.

  • Some GB standards are directly mandatory for market access and safety.

Bottom line:
BS = UK/European-oriented system.
GB = Chinese national system, tightly coupled to Chinese regulations.

3.2 Relationship to ISO / EN

• BS

  • Many BS standards are identical adoptions of EN or ISO (e.g. BS EN 755, BS EN ISO 9001).

  • Technical content is usually the same as the EN/ISO parent.

• GB / GB-T

  • Can be:

    1. Identical adoption of ISO.

    2. Modified adoption (based on ISO but adjusted).

    3. Fully independent Chinese standard, only referencing ISO/EN as background.

So “same topic” does not guarantee “same content” between BS and GB/T.

3.3 Technical Content and Design Philosophy

Even on the same product type (for example aluminium extrusions), BS EN and GB/GB-T can differ in:

1. Scope

   • BS EN 755 covers wrought aluminium products (bars, profiles, tubes).

   • GB/T 6892 covers aluminium extruded profiles for general engineering.
     The coverage and limitations are not necessarily identical.

2. Alloy designation and chemistry

   • BS side: EN/ISO alloy system (e.g. EN AW-6063), with composition in EN 573.

   • GB side: Chinese alloy system linked to GB/T 3190 (6063, 6061 etc.), with possibly different composition ranges.

3. Mechanical properties

   • Minimum yield, tensile strength and elongation values can differ.

   • Requirements may depend on direction (longitudinal / transverse) in different ways.

4. Dimensional tolerances

   • BS EN uses its own tolerance system (e.g. EN 755-9 for profiles).

   • GB/GB-T has its own tolerances for dimensions, straightness, twist, etc.
     They are similar in spirit but not guaranteed numerically identical.

5. Testing and inspection rules

   • Sampling frequency, type of certificates, test methods referenced can differ.

3.4 Numbering, Structure and Referencing

• BS example

  • BS EN 755-2:2016 – part of a European series adopted by the UK.

  • Often references other standards like BS EN 10204 for inspection documents.

• GB example

  • GB/T 6892-2015 or GB/T 5237.1-2017 – national or multi-part standards.

  • Frequently references other GB/GB-T standards for testing (e.g. GB/T 228 for tensile tests, GB/T 3190 for composition).

4. Example: Aluminium Extrusions (BS vs GB/T)

BS / EN side

• BS EN 755 series for wrought aluminium products:

  • EN 755-1: General

  • EN 755-2: Mechanical properties

  • EN 755-9: Dimensional tolerances for extruded profiles

Typical specification:

EN AW-6063 T66 extruded profile
in accordance with BS EN 755-2 and BS EN 755-9.

GB side

• GB/T 6892 – Aluminium and aluminium alloy extruded profiles – general engineering.

• Often combined with GB/T 3190 (chemical composition).

Typical specification:

6063-T6 aluminium alloy profiles
in accordance with GB/T 6892 and GB/T 3190.

Important:
Even if the alloy name looks the same (“6063-T6”), the exact mechanical properties, tolerances and test requirements in BS EN vs GB/T may not match.

5. Practical Tips When Converting Between BS and GB/T

1. Never assume “equivalent” without checking.
   Do not simply write “BS XXX = GB/T YYY” unless the standard clearly says it is an identical adoption.
   Otherwise, treat them as similar but not automatically equivalent.

2. When comparing, always check at least:

   • Scope (what products / conditions are covered).

   • Alloy / material definitions and chemistry.

   • Mechanical property values and test directions.

   • Dimensional tolerances and straightness/twist limits.

   • Test methods, sampling and inspection/Certification requirements.

3. Be explicit in drawings and contracts.

   Example – BS route:

   Profiles: EN AW-6063 T66 per BS EN 755-2 and BS EN 755-9.

   Example – GB route:

   Aluminium alloy profiles: 6063-T6 per GB/T 6892 and GB/T 3190.

   If you must accept both, you can state that properties and tolerances must not be lower than the chosen reference (e.g. the BS EN requirements).

4. Check certification format.

   • BS / EN often uses EN 10204 (2.2 / 3.1 certificates).

   • GB may use “material certificate / quality certificate” with similar content but different format.

   • If needed, require that the GB-side certificate contains the same key data as an EN 10204 3.1 certificate.

Short Summary

• BS standards: British implementation of EN/ISO, aligned with European practice.

• GB / GB-T standards: Chinese national standards, aligned with Chinese laws and industry norms.

• For the same type of product (e.g. aluminium extrusions), BS EN and GB/GB-T standards can differ in scope, chemistry, mechanical properties, tolerances and inspection rules, so you should compare them item by item and clearly specify which system you are using in your drawings and contracts.