Question regarding the thickness of blind plates for pipeline pressure testing

Please see the following post； http://bbs.hcbbs.com/viewthread.php?tid=192562

Blind plate management: I. Definition of temporary blind plates Insertable steel plate blind plates, flat-plate welded steel plate blind plates, and semi-circular head welded blind plates that are used during pipeline testing (purging); as well as partitions used to prevent debris and welding slag from entering equipment, containers, and machinery during pipeline grinding, repair, and welding – all of these are referred to as temporary blind plates. II. Procedures and Responsibilities for Temporary Blind Flanges (I) Fabrication and Installation of Temporary Blind Flanges 1. For the plug-type steel plate blind flanges, flat-plate welded steel plate blind flanges, and semi-circular head welded blind flanges used during pipeline testing (purging), the technical personnel assigned to the project team calculate the specifications of the temporary blind flanges, the type of groove, the strength of the welds, the bolt sizes, etc., in accordance with the requirements outlined in the pipeline design manual. The specifications, quantity, and application locations of the temporary blind plates shall be included in the construction plan. Construction can only proceed after calculation and approval by the project chief engineer or the technical supervisor in charge of the project. 2. The technical staff of the project team, prior to the fabrication of temporary blind plates, provide technical instructions to the construction teams (including labor teams and subcontracted teams) by combining pipeline layout diagrams with record sheets. The details covered in these instructions include the specifications, material type, quantity of temporary blind plates, bolt specifications, locations where they will be used, groove shapes, and welding requirements. The workshop technicians and quality inspectors supervise the construction teams (including labor teams and subcontracted teams) to post the instruction cards and record sheets on the walls of the team rest rooms, so that all team members are aware of the areas where temporary blind plates will be used. The technical supervisor and quality supervisor of the project department inspect the situation regarding technical instructions. 3. Once the temporary blind plates are manufactured by the construction teams (including labor teams and subcontracted teams), they are assigned uniform numbers; these numbers are marked on the center of the blind plates, and a record sheet detailing the locations where the temporary blind plates will be used is filled out (see attached form). Technicians with project team work IDs and inspectors on the project carry out supervision and inspection. 4. When installing temporary blind plates, the operators of the project team shall label them according to the numbers listed in the record sheet, and fill out the record sheet indicating the location where the temporary blind plates are used at all times (see attached sheet). The supervisors of the project team’s construction teams (including labor teams and subcontracted teams), the technical officers assigned to each worker, and the inspectors from the project department shall inspect these blind plates one by one and sign to confirm them. 5. After the installation of the temporary blind plates is completed, the project team shall submit one copy of the record sheet detailing the locations where these temporary blind plates are used (see attached table) to both the technical supervisor and the quality supervisor of the project department. The record sheet should also be posted on the wall in the project department’s dispatch room (see attached table). (II) Removal of temporarily installed blind flanges: 1. When the construction teams (including labor teams and subcontracted teams) remove the temporarily installed blind flanges, the technical officers assigned to the project team monitor the process, make markings on the record sheet for the locations where these temporary blind flanges are used (see attached form), while the quality inspection staff from the project department supervise the operation. 2. After all temporary blind plates have been removed, the project’s chief engineer or technical supervisor shall organize relevant personnel to conduct a joint inspection to confirm that nothing has been overlooked. Only after such inspection confirms the absence of any issues should the record sheet indicating the locations where temporary blind plates were used, which is attached as an appendix, be signed for confirmation on the wall in the project management office. The record sheet shall be kept by the person in charge of project quality, and it may be destroyed only after the chemical materials have been supplied. III. Management of Temporary Blind Flange Marking (I) Hardware Marking 1. All temporary blind flanges used on site must be equipped with labels. The signs are made of galvanized iron sheet with a thickness of δ=0.25～0.5, and the numbers are printed on them using steel typefaces. 2. The plug-type blind flanges and blind flange gaskets used on site must have handles when being delivered (referred to at the construction site as blind flanges with tails). (II) Software identification: All temporary blind plates in use at the site must be marked on the process pipeline schematic diagram or equipment diagram.

GB50316－2000 \"Code for Design of Industrial Metal Piping\", 6.7.2: The calculated thickness of a blind plate located between two flanges can be determined using Equation 1. When manufactured using a solid steel plate, the welding joint coefficient E in the formula is equal to 1. For permanent blind plates, an additional thickness should be added according to Equation 2. tm=0.433d *E）]0.5 (Equation 1) 6.7.2 tp= tm +2C2+C1 (Equation 2) tm—Calculated thickness of the blind plate (mm); d—Inner diameter of the concave or flat flange gasket, or average diameter of the ring-type gasket (mm); P—Design pressure (MPa); σ—Allowable stress of the material at the design temperature (MPa). For hot-rolled plates of Q235-A, B, the allowable stress is 113 MPa for temperatures up to 100°C. tp—Designed thickness of the blind plate (mm); C2—Corrosion amount or additional amount due to corrosion (mm); C1—Additional amount resulting from thickness reduction (mm). Flat gaskets 6.6.1 The thickness of flat gaskets without welded joints shall be calculated using Equation 1 and Equation 2. tm = [K(D + 2C) * η]0.5 (Equation 1)
tp = tm + C (Equation 2)
tp: Design thickness of the flat cover (mm)
tm: Design thickness of the flat cover (mm)
D: Inner diameter of the pipe (mm)
K, η: Coefficients related to the structure of the flat cover; values to be selected from the table below.
P: Design pressure (MPa)
σ: Allowable stress of the material at the design temperature (MPa)
For hot-rolled plates of type Q235-A, B, at temperatures up to 100°C, the allowable stress is 3–40 mm; σ = 113 (MPa)
C: Total amount of additional thickness (mm)

Where can I find guidelines to study*?