GB/T 9842-2018 (English Version)

Standard No.: GB/T 9842-2018
Language: Chinese, Available in English version
Release Date: 2018
Published By: General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
Latest: GB/T 9842-2018
Replace: GB/T 9842-2004

Scope: This standard specifies the requirements for urea synthesis towers in urea plants, hydraulic pressure tests and leakage tests, pickling and passivation of stainless steel, painting, packaging, transportation, marking and factory technical documents. This standard applies to urea synthesis towers lined with urea grade ultra-low carbon austenitic stainless steel with a design pressure not exceeding 21.6 MPa and a design temperature not exceeding 200°C.

Introduction

GB/T 9842—2018 Standard Overview

The National Standard of the People's Republic of China GB/T 9842—2018 "Technical Conditions for Urea Synthesis Tower" was issued in 2018, replacing the old standard GB/T9842—2004. This standard specifies in detail the design, manufacturing and inspection requirements for urea synthesis towers, especially the selection of stainless steel materials, processing technology and performance testing.

Main differences compared with the old version of the standard

Revision dimensions	Requirements of the 2004 version	New requirements of the 2018 version
Design temperature limit	Specific limit is not specified	Specify that the design temperature is not greater than 200°C
Stainless steel material standards	Requirements for urea-grade austenitic stainless steel are not involved	Requirements for urea-grade 00Cr17Ni14Mo2 and 00Cr25Ni22Mo2 are added
Welding material composition	Table 2 has relatively simple regulations	The chemical composition of welding rods and welding wires is refined, and new requirements for N content are added

Interpretation of core technical requirements

1. Material selection and performance testing

The standard requires that the pressure components and corrosive medium contact parts of the urea synthesis tower must use specific urea-grade austenitic stainless steel (such as 00Cr17Ni14Mo2 and 00Cr25Ni22Mo2). These materials must meet the following requirements:

Chemical composition complies with the requirements of Table 1
The ratio of ferrite-forming elements to austenite-forming elements is appropriate to ensure full austenite structure
The intergranular corrosion rate CR does not exceed 1.0 μm/48h

Implementation suggestions

To ensure that the urea synthesis tower complies with the GB/T 9842-2018 standard, the following measures are recommended:

Strict material acceptance: Re-inspect the furnace number and analyze the chemical composition of the purchased stainless steel materials.
Optimize welding process: Use strip electrode automatic cladding technology to ensure that the thickness of the transition layer and the corrosion-resistant layer meet the standards.
Strengthen non-destructive testing: Use ultrasonic, radiographic and penetrant testing to comprehensively evaluate the quality of the weld.
Standardized heat treatment process: Perform stress relief heat treatment at the temperature specified in Table 4 to avoid multiple heating damage.

GB/T 9842-2018 Referenced Document

GB/T 1220 Stainless steel bars
GB/T 13296 Stainless steel seamless steel pipes for boilers and heat exchangers*， 2023-11-27 Update
GB/T 14976 Seamless stainless steel pipes for fluid transport
GB/T 25150 Test method for quality of passivation film on austenitic stainless steel in chemical cleaning of industrial equipment blue dot method
GB/T 25151.1 Fabrication and inspection method for high pressure urea equipment.Part 1:Ultrasonic examination on the automatic strip overlay welds of stainless steel
GB/T 25151.2 Fabrication and inspection method for high pressure urea equipment.Part 2:Selective corrosion examination and metallography examination for ultra low-carbon chromated nickel molybdenum austenitic stainless steel of urea grade
GB/T 25151.3 Fabrication and inspection method for high pressure urea equipment.Part 3:Intergranular corrosion tendency test for ultra low-carbon chromated nickel molybdenum austenitic stainless steel of urea grade
GB/T 25151.4 Fabrication and inspection method for high pressure urea equipment.Part 4:Intergranular corrosion tendency test specimen preparation for ultra low-carbon chromated nickel molybdenum austenitic stainless steel of urea grade
GB/T 25151.6 Fabrication and inspection method for high pressure urea equipment.Part 6:Helium leakage test method for urea high pressure equipment
GB/T 25198 Pressure vessel head*， 2023-08-06 Update
GB/T 4226 Cold finished stainless steel bar
GB/T 5777-2008 Ultrasonic testing method for seamless steel pipe
GB/T 983 Covered electrodes for manual metal arc welding of stainless and heat-resisting steels
HG/T 3179 Urea high-pressure equipment surfacing process assessment and welder skill assessment*， 2023-12-20 Update
HG/T 3180 Welding process assessment and welder skill assessment of lining plates and internal parts of urea high-pressure equipment*， 2023-12-20 Update
JB/T 4711 Coating and packing for pressure vessels transport
NB/T 47013.1 Nondestructive testing of pressure equipments.Part 1: General requirements
NB/T 47013.2-2015 Nondestructive testing of pressure equipments.Part 2: Radiographic testing
NB/T 47013.5-2015 Nondestructive testing of pressure equipments.Part 5: Penetrant testing
NB/T 47016 Mechanical properties test of welded specimens of pressure equipment products*， 2023-12-28 Update

GB/T 9842-2018 history

2018 GB/T 9842-2018 Specification for urea reactor
2004 GB/T 9842-2004 Specification for urea reactor
1988 GB 9842-1988 Specifications for urea reactor