GB/T 30789.4-2015 English PDF (GBT30789.4-2015)

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GB/T 30789.4-2015: Paints and varnishes -- Evaluation of degradation of coatings -- Designation of quantity and size of defects, and of intensity of uniform changes in appearance -- Part 4: Assessment of degree of cracking
GB/T 30789.4-2015
GB
NATIONAL STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 87.040
G 50
GB/T 30789.4-2015 / ISO 4628-4.2003
Paints and varnishes - Evaluation of degradation of
coatings - Designation of quantity and size of defects,
and of intensity of uniform changes in appearance -
Part 4. Assessment of degree of cracking
(ISO 4628-4.2003, IDT)
ISSUED ON. JULY 3, 2015
IMPLEMENTED ON. FEBRUARY 1, 2016
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Assessment ... 5 
5 Expression of results ... 8 
6 Test report ... 8 
Annex A (Informative) Examples of types of cracking ... 9 
Foreword
GB/T 30789 Paints and varnishes - Evaluation of degradation of coatings -
Designation of quantity and size of defects, and of intensity of uniform changes
in appearance consists of the following parts.
- Part 1. General introduction and designation system;
- Part 2. Assessment of degree of blistering;
- Part 3. Assessment of degree of rusting;
- Part 4. Assessment of degree of cracking;
- Part 5. Assessment of degree of flaking;
- Part 6. Assessment of degree of chalking by tape method;
- Part 7. Assessment of degree of chalking by velvet method;
- Part 8. Assessment of degree of delamination and corrosion around a
scribe or other artificial defects;
- Part 9. Assessment of degree of filiform corrosion.
This Part is the fourth part of GB/T 30789.
This Part was drafted in accordance with the rules given in GB/T 1.1-2009.
This Part uses translation method and identically adopts ISO 4628-4.2003
Paints and varnishes - Evaluation of degradation of coatings - Designation of
quantity and size of defects, and of intensity of uniform changes in appearance
- Part 4. Assessment of degree of cracking.
This Part was proposed by China Petroleum and Chemical Industry Federation.
This Part shall be under the jurisdiction of National Technical Committee on
Paints and Pigments of Standardization Administration of China (SAC/TC 5).
The drafting organizations of this Part. CNOOC Changzhou Paint and
Chemicals Research Institute Co., Ltd., China Zhiqi (Shenzhen) Co., Ltd.,
Guangzhou Synthetic Material Research Institute Co., Ltd., AVIC Bermuda New
Material Technology Engineering Co., Ltd., Zhejiang Yutong New Material Co.,
Ltd., Dongguan Yian Technology Co., Ltd..
Main drafters of this Part. Zhang Ping, Cheng Hongqi, Wen Jing, Shi Hua, Yang
Yaliang, Tang Tiezhuang.
Paints and varnishes - Evaluation of degradation of
coatings - Designation of quantity and size of defects,
and of intensity of uniform changes in appearance -
Part 4. Assessment of degree of cracking
1 Scope
This Part of GB/T 30789 describes a method for assessing the degree of
cracking of coatings by comparison with pictorial standards, using the
designation system defined in GB/T 30789.1.
ISO 4628-1 defines the system used for designating the quantity and size of
defects and the intensity of changes in appearance of coatings and outlines the
general principles of the system. This system is intended to be used, in
particular, for defects caused by ageing and weathering, and for uniform
changes such as colour changes, for example yellowing
2 Normative references
The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies.
ISO 4628-1, Paints and varnishes - Evaluation of degradation of coatings -
Designation of quantity and size of defects, and of intensity of uniform
changes in appearance - Part 1. General introduction and designation
system
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 degree of cracking
rating characterizing cracks in a coating in terms of quantity, size and depth