This standard specifies the technical requirements for pickling preparation, pickling, pickling buckle treatment, tank liquid management, surface condition after pickling, safety, environment, etc. This standard applies to the pickling of steel parts before painting. JB/T 6978-1993 Surface preparation before painting Pickling JB/T6978-1993 Standard download decompression password: www.bzxz.net
This standard specifies the technical requirements for pickling preparation, pickling, pickling buckle treatment, tank liquid management, surface condition after pickling, safety, environment, etc. This standard applies to the pickling of steel parts before painting.

Machinery Industry Standard of the People's Republic of China
JB/T 697893
Surface preparation before painting - pickling
Published on July 27, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1994
Mechanical Industry Standard of the People's Republic of China
Surface preparation before painting - pickling
1 Subject content and scope of application
JB/T6978-93
This standard specifies the technical requirements for pickling preparation, pickling, post-pickling treatment, tank liquid management, surface condition after pickling, safety, environment, etc.
This standard applies to pickling of steel parts before painting. 2 Reference standards
GB6807
GB7692
GB7693
JB/Z236
Preparation before pickling
Technical conditions for phosphating of steel parts before painting Process safety before painting
Process ventilation and purification before painting
Test method for the degree of degreasing of steel parts before painting 3.1 Use organic solvents, alkaline degreasing agents or surfactants to remove heavy oil scale, grease, processing fluid and other dirt attached to the surface of the steel parts to be pickled, and test according to JB/Z236. bZxz.net
3.2 Use any method such as manual or mechanical to remove heavy rust, thick oxide scale or organic coating on the surface of the steel parts to be pickled to shorten the pickling time. 4 Pickling
4.1 The pickling solution is prepared by a certain concentration of acid, generally hydrochloric acid, sulfuric acid, phosphoric acid or a mixed acid thereof. In order to prevent excessive corrosion and reduce hydrogen, corrosion inhibitors need to be added to the pickling solution. In order to prevent acid mist, acid mist inhibitors can be added to the pickling solution. The usage and dosage must comply with the product instructions.
4.2 The concentration of the pickling solution, working temperature, and pickling time are determined by the surface conditions of the steel. The composition of the pickling solution and its working specifications, the types of corrosion inhibitors used, and the usage are shown in Appendix A (reference). 5 Post-pickling treatment
5.1 In order to reduce the amount of acid brought into the rinse tank, the steel parts can be briefly left above the pickling tank after being taken out of the pickling tank to drip off most of the acid remaining on the steel parts.
5.2 After pickling, the steel parts need to be fully cleaned with clean water at a temperature between room temperature and 80°C. In order to maintain the surface condition of the steel parts after pickling, the steel parts after water washing need to be immediately neutralized, phosphated or passivated according to the coating requirements. Phosphating is carried out in accordance with GB6807. 5.3 After pickling, the steel parts should be piled up after being completely dried, and the coating should be carried out as soon as possible to prevent re-contamination. 6 Management of tank liquid
6.1 The changes of pickling tank liquid should be checked regularly, and its iron ion content should not exceed the provisions of the following table. Approved by the Ministry of Machinery Industry on July 27, 1993
Implementation on July 1, 1994
JB/T697893
Iron ion content
To ensure the cleaning quality of steel parts after pickling, the total amount of acid and salt accumulated in the cleaning tank should not exceed 0.2% m/m. Surface condition after pickling
If there is no other agreement between the supply and demand parties, the surface condition of steel parts after pickling and post-treatment shall meet the requirements of Appendix B (reference part). Safety and environmental requirements
8.1 Pre-treatment for painting - Safety regulations for pickling process shall be in accordance with the provisions of Chapter 8 of GB7692. 8.2 The environmental requirements for the pickling process before painting shall comply with the provisions of Chapter 5 of GB7693. 2
Hydrochloric acid (37% m/m)
Concentration: 20%~40% m/m
Centerology: room temperature~40℃
JB/T 6978-93
Appendix A
Pickling solution composition and working specifications,
Types and amounts of corrosion inhibitors used
(reference)
Time:>10min(with complete rust removal as the principle)
Corrosion inhibitor: hexamethylenetetramine and other corrosion inhibitors suitable for hydrochloric acid solution, the amount shall not exceed 0.05%~0.5%m/m of the acid amount
Sulfuric acid (98%m/m)
Degree of concentration: 10%~30%m/m
Degree of concentration: 50~75℃| |tt||Time:>3min (based on the principle of removing all rust)
Corrosion inhibitor: thiourea, rhodamine, etc., the amount does not exceed 0.05%~0.5% of the acid amount m/m Phosphoric acid (85% m/m)
Degree: 10%~30% m/m
Degree: room temperature~60℃
Time: 5~20min (based on the principle of removing all rust)Corrosion inhibitor: sulfur, hexamethylenetetramine, etc., the amount does not exceed 0.05%~0.5% of the acid amount m/m Hydrochloric acid-sulfuric acid (mixed acid))
Degree: hydrochloric acid (3 7%): 5%~40%m/m
Sulfuric acid (98%): 5%~20%m/m
Temperature: room temperature~40℃
Time:>2min(based on the principle of removing all rust)Corrosion inhibitor; refer to the applicable types and dosage ranges of each single acid solutionPhosphoric acid-citric acid (mixed acid solution)
Concentration: Phosphoric acid (85%): 5%~30%m/mCitric acid (98%): 1%~10%m/m
Degree: room temperature~60℃
Time:>5min(based on the principle of removing all rust) )
Corrosion inhibitor: refer to the applicable types and dosage ranges of each single acid solution. Types of acid solution
Additional instructions:
JB/T6978-93
Appendix B
Surface condition of steel parts after pickling
(reference part)
Surface condition
The surface should be uniformly silver, with basically no black dusting. The surface should be uniformly light gray, with basically no black dusting. The surface should be uniformly light gray, with basically no black dusting. This standard was proposed and managed by Wuhan Institute of Material Protection. This standard was drafted by Wuhan Institute of Material Protection. The drafters of this standard are Huang Minghua, Xiong Shaoqian, and Gong Maochen. People's Republic of China
Mechanical Industry Standard
Surface preparation before painting - pickling
JB/T6978-93
Published and distributed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry Printed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry (P.O. Box 8144, Beijing
Copyright reserved
Postal Code 100081)
No reproduction
Format 880×12301/16
Sheet 1/2 Number of words 8,000
First edition in April 1994
First printing in April 1994
Print run 00,001500
Price 3.00 Yuan
No. 1422
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