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GB/T 37589-2019 (GB/T37589-2019)

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GB/T 37589-2019: PDF in English (GBT 37589-2019)
GB/T 37589-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.220.99
A 29
Technical specification for anticorrosion of steel pipe
and fitting lining with fluoroplastics
ISSUED ON: JUNE 04, 2019
IMPLEMENTED ON: MAY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 6 
4 General requirements ... 7 
5 Lining work ... 9 
6 Product inspection ... 15 
7 Environmental protection ... 16 
8 Safety ... 16 
Technical specification for anticorrosion of steel pipe
and fitting lining with fluoroplastics
1 Scope
This Standard specifies general requirements for anticorrosion of steel pipe and
fitting lining with fluoroplastics, lining operations, product inspection,
environmental protection, safety requirements.
This Standard is applicable to pipe and pipe fitting drawing, roto-molding,
molding, spraying, plate lining, isostatic pressing, injection molding, transfer of
fluoroplastic lining.
NOTE: Fluoroplastics include the following: polytetrafluoroethylene (PTFE), modified
polytetrafluoroethylene (M-PTFE), soluble polytetrafluoroethylene (PFA), polyvinylidene
fluoride (PVDF), perfluoroethylene propylene copolymer (FEP), ethylene-
tetrafluoroethylene copolymer (ETFE).
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.
GB/T 1033.1, Plastics - Methods for determining the density of non-cellular
plastics - Part 1: Immersion method liquid pycnometer method and titration
method
GB/T 8163, Seamless steel pipes for liquid service
GB/T 8923.1, Preparation of steel substrates before application of paints and
related products - Visual assessment of surface cleanliness - Part 1: Rust
grades and preparation grades of uncoated steel substrates and of steel
substrates after overall removal of previous coatings
GB 9448, Safety in welding and cutting
GB 12348-2008, Emission Standard for Industrial Enterprises Noise at
Boundary
GB/T 12459, Steel butt-welding seamless pipe fittings
ASTM D3159, Standard specification for modified ETFE fluoropolymer
molding and extrusion materials
ASTM D3222, Standard specification for unmodified poly (vinylidene fluoride)
(PVDF) molding extrusion and coating materials
ASTM D3307, Standard specification for perfluoroalkoxy (PFA)-fluorocarbon
resin molding and extrusion materials
ASTM D4894, Standard specification for polytetrafluoroethylene (PTFE)
granular molding and ram extrusion materials
ASTM D5575, Standard classification system for copolymers of vinylidene
fluoride (VDF) with other fluorinated monomers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 matrix
Steel pipe and fitting before lining.
3.2 lining thickness
Lining layer thickness of steel-plastic composite pipe.
3.3 drawing molding
Lining process that allows a seamless gap between the lining layer and the
matrix through a certain mechanical method.
3.4 wrapping
Lining process that uses thermal expansion to make the fluoroplastic film tightly
merged.
3.5 roto-lining
Composite tight lining process that the plastic powder is the main raw material,
and the multi-directional rotary hot-melt technology has a certain peel strength
after multiple feedings and one-time molding.
3.6 transfer molding
Process that melts and extrudes plastic pellets into molds and then cools and
demolds.
serious break in the matrix, and the specifications meet the requirements of the
production record table.
5.2.1.2 Fix specific fixture to fluoroplastic tube. Slowly pull the fluoroplastic tube
into the matrix through the stretching equipment, so that the fluoroplastic tube
and the matrix are tightly combined.
5.2.1.3 After completion, check whether the inner wall of the liner is flat and
smooth. The scratch depth of the reserved outer end of the drawn tube shall
not exceed 10% of the tube wall thickness. Then reserve enough flanging
amount for the edges of the fluoroplastic tube. For nonconforming products, pull
the liner tube out of the steel base again and restart the tube drawing operation.
5.2.1.4 Conduct annealing and stress-relieving for the matrix with conforming
lining. The temperature is 150°C~250°C.
5.2.1.5 Heat the composite straight tube after stress relief to 150°C~300°C
(according to different materials) after flanging. Cool and mold.
5.2.1.6 The minimum thickness of the lining after molding shall meet the
requirements of 5.4. The minimum outer diameter of the sealing surface shall
meet the requirements of 5.5. The scratches and depressions of the flanging
surface shall not exceed 20% of the wall thickness.
5.2.2 Iso-static lining of fittings
5.2.2.1 Assemble conforming matrix and elastic mold.
5.2.2.2 Inject plastic powder into the module gap. Plastic powder shall be clean
and free of impurities. Then blindly put it into the pressure tank and slowly
pressurize it to 15MPa~35MPa. Slowly relieve the pressure after holding
pressure for 10min~30min.
5.2.2.3 Check the inner wall for cracks, impurities and other bad phenomena. If
there are, it shall return to work.
5.2.2.4 Sinter the conforming matrix after molding according to the parameters
in Table 5 or the sintering parameters provided by the raw material manufacturer.
5.2.2.5 Check the inner wall after sinter cooling. There shall be no cracks on
the surface of the fluoroplastic, and the thickness shall meet the technical
specifications or contract requirements.
5.2.3 Sheet lining of pipes and fittings
5.2.3.1 Apply conforming adhesive to the inner surface of the conforming matrix.
The thickness of the adhesive shall be tested after ventilating and drying.
Continue working only after it meets the requirements of the enterprise standard.
There must be no bad phenomena such as impurities and cracks.
5.2.5.5 The minimum thickness of the lining after molding shall meet the
requirements of 5.4. The minimum outer diameter of the sealing surface shall
meet the requirements of 5.5. The scratches and depressions of the flanging
surface shall not exceed 20% of the wall thickness.
5.2.6 Roto-lining of pipes and fittings
5.2.6.1 Install conforming matrix on roto-molding machine. After heating to the
sintering temperature, it rotates and revolves simultaneously.
5.2.6.2 Put the screened powder into the matrix. At the same time continue to
use the sintering temperature to rotate and revolute.
5.2.6.3 When the raw material is naturally and evenly attached to the matrix
lining surface, then remove the heat source. Slowly cool down while rotating.
5.2.6.4 After cooling, inspect the rotomolded lining surface for cracks and
impurities, and the wall thickness is uniform.
5.2.6.5 If the inspection is conforming, the sealing surface shall be conducted
for plane processing to ensure the tightness.
5.2.6.6 The minimum thickness of the lining after molding shall meet the
requirements of 5.4. The minimum outer diameter of the sealing surface shall
meet the requirements of 5.5. The scratches and depressions of the flanging
surface shall not exceed 20% of the wall thickness.
5.2.7 Coating lining of pipes and fittings
5.2.7.1 The matrix shall be preheated to evaporate water before powder coating.
Preheating temperature is 150°C~300°C.
5.2.7.2 Before liquid spraying, mix the prepared compound fluoroplastic coating
30min~60min in advance evenly.
5.2.7.3 Spray to the surface of conforming matrix to reach the thickness of
single mode and sinter. The thickness of powder single mode is generally
50μm~150μm. The thickness of liquid single mode is 15μm~40μm. The
sintering temperature is set according to the parameters in Table 5 or according
to the sintering parameters provided by the raw material manufacturer.
5.2.7.4 After the single film is sintered, check the surface for cracks and sand
holes and then continue working.
5.2.7.5 Repeat 5.2.7.3 and 5.2.7.4. In the meantime, use the thickness gauge
to test the thickness in multiple areas and points until the required thickness is
......
 
(Above excerpt was released on 2020-07-13, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT37589-2019