Lined butterfly valve and method for manufacturing lined butterfly valve

1. A lined butterfly valve comprising:

a body;

a stem rotatably mounted in the body; and

a valve disk provided rotatably inside the body via the stem, the valve disk including a core metal covered with a lining layer,

wherein the lining layer comprises a front/back-side lining part provided on each of a front side and a back side of the core metal, and an outer circumferential lining part provided on an outer circumferential side of the core metal,

wherein the front/back-side lining part is provided on each of the front and back sides of the core metal, so as to have a thickness obtained by adding a first predetermined lining thickness and a thickness equal to a maximum warp width on a valve blade side of the core metal at least at an outer circumferential end position of the core metal,

wherein the outer circumferential lining part has a thickness from an outer circumferential end of the core metal to a tip seal surface of an outer circumferential end of the valve disk obtained by adding a second predetermined lining thickness and a predetermined crush thickness,

wherein each predetermined lining thickness is a minimum thickness required so as to prevent a fluid from permeating through the core metal,

wherein the maximum warp width is a deviation amount due to a maximum warpage of the core metal that occurs during casting of the core metal or during a lining process, and

wherein the predetermined crush thickness is an amount of irreversible crush of a convex part on the outer circumference of the valve disk that occurs when the valve disk is opened and closed.

2. The lined butterfly valve according to claim 1 , wherein the outer circumferential lining part has the convex part protruding to an outer circumferential side of the valve disk, the convex part substantially annularly formed contiguously protruding to an outer circumference of the valve disk, and an end face of the convex part on the outer circumferential side of the valve disk serves as the tip seal surface having a predetermined seal width.

3. The lined butterfly valve according to claim 2 , wherein each side surface part of the convex part with respect to the tip seal surface is formed of a tilted surface having an angle equal to or smaller than 10 degrees with respect to a pressure-contact seal direction of the tip seal surface.

4. The lined butterfly valve according to claim 2 , wherein the core metal has an outer circumferential side surface part on its outermost circumference, and the outer circumferential side surface part has a width such that the outer circumferential side surface part can oppose a center part of the convex part in a thickness direction of the outer circumferential lining part.

5. The lined butterfly valve according to claim 4 , wherein the valve blade side of the core metal is warped to the maximum warp width.

6. The lined butterfly valve according to claim 1 , wherein one set of washers opposed to each other in a direction of insertion of the stem is attached in a shaft-mounting part where the stem is inserted, wherein the one set of washers is formed of convex and concave shapes so that a surface pressure applied from the stem side to a boss part formed in the valve disk can be substantially equal even when a deviation or tilt occurs between the stem and the valve disk.

7. The lined butterfly valve according to claim 6 , wherein the one set of washers is formed of a convex-shaped washer including a convex spherical surface and a concave-shaped washer including a concave spherical surface with which the convex spherical surface is in surface contact, wherein the convex-shaped washer and the concave-shaped washer are attached in a pressurized state in a mutually opposed direction by a spring-back force of a spring inserted in the shaft-mounting part.

8. A method for manufacturing the lined butterfly valve according to claim 1 , comprising:

inserting the stem or a stem jig having a same shape as the stem in stem insertion holes provided to the core metal at opposing positions of a valve blade part of the core metal to fix the core metal and the stem or the stem jig to each other;

arranging the core metal in a molding space of a die for molding the lining layer; and

in a state in which the stem or the stem jig is held so that the core metal is fixed so as not to move in the molding space, introducing a material for forming the lining layer into the molding space to form the lining layer on a surface of the core metal.

9. A lined butterfly valve comprising:

a body;

a stem rotatably mounted in the body; and

a valve disk provided rotatably inside the body via the stem, the valve disk including a core metal covered with a lining layer,

wherein the lining layer comprises a front/back-side lining part provided on each of a front side and a back side of the core metal, and an outer circumferential lining part provided on an outer circumferential side of the core metal,

wherein the front/back-side lining part has at least a first predetermined lining thickness on each of the front and back sides of the core metal and has, at least at an outer circumferential end position of the core metal, in total on the front and back sides, a thickness obtained by doubling a thickness obtained by adding a thickness equal to a maximum warp width on a valve blade side of the core metal to the first predetermined lining thickness,

wherein the outer circumferential lining part has a thickness from an outer circumferential end of the core metal to a tip seal surface of an outer circumferential end of the valve disk obtained by adding a second predetermined lining thickness and a predetermined crush thickness,

wherein each predetermined lining thickness is a minimum thickness required so as to prevent a fluid from permeating through the core metal,

wherein the maximum warp width is a deviation amount due to a maximum warpage of the core metal that occurs during casting of the core metal or during a lining process, and

wherein the predetermined crush thickness is an amount of irreversible crush of a convex part on an outer circumference of the valve disk that occurs when the valve disk is opened and closed.