1. Scope of Application
This Standard specifies the requirements for shipbuilding cast iron 5K gate valves (hereafter referred to as "valves") used for steam pipes, fuel oil pipes, lubricating oil pipes, fresh water pipes, feed water pipes, etc., on ships.

2. Relationship between Fluid Condition and Maximum Working Pressure 
The relationship between the fluid condition and the maximum working pressure is as follows:

3. Construction, Shape and Dimensions
The construction, shape, and dimensions of the valves shall conform to the attached drawings 1 and 3, in addition to the need to install appropriate ribs on the valve body, bonnet, and disc. The tolerance for wall thickness is generally +10% to -10%. However, if the calculated wall thickness is less than 1 mm, it is permitted to be 1 mm.
For the opening/closing mechanisms with DN 450 to 600, if the working pressure is 0.2 MPa or less, the sliding thrust bearing may be omitted at the discretion of the purchaser, allowing for direct opening/closing by handwheel.

4. Materials
The materials for the main parts are as follows:
(1) The main parts for valve boxes and bonnets are divided into the B Series and S Series depending on the material combination.
(2) Other materials generally conform to the attached drawings 2 and 4.

• Body / Bonnet (B Series): JIS G 5501 FC200 (Grey iron castings)

• Body / Bonnet (S Series): JIS G 4303 SUS403 or SUS410J2 (Stainless steel)

• Disc (Wedge): JIS G 5501 FC200 (B) or JIS G 4303 SUS403 (S)

• Stem: JIS G 4303 SUS403 (Martensitic) or SUS304 (Austenitic)

• Seat Ring: JIS H 5111 BC6 (Bronze castings) or JIS G 4303 SUS403

• Handwheel: JIS G 5501 FC200

• Packing / Gaskets: Per JIS F 7102

5. Inspection
Valve inspection is conducted per JIS F 7400, covering the following five items:

1. Material inspection

2. Visual inspection

3. Dimensional inspection

4. Assembly inspection

5. Hydrostatic (Pressure) testing
   For the hydrostatic test, the test pressure per Table 2 is applied. For valves with a nominal diameter (DN) of 300 or more, the seat leakage test pressure may be specified by the purchaser.

Table 2: Test Pressure (MPa)

6. Product Designation
The product designation shall be the standard name, or its abbreviation, or the series code plus nominal diameter and material series code.
Example 1: Cast iron 5K-50 gate valve, or FS 5050 B, or JIS F 7363-50B.
(Where 50 = Nominal Diameter, B = Material Series)
Example 2: Cast iron 5K-450 gate valve (with sliding thrust bearing), or FS 5450 ST, or JIS F 7363-450ST.