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Soft sealing butterfly valve introduction

2021-09-24
Soft sealing butterfly valve usually used in medicine, chemical, petroleum, electricity, textile, paper industry .Its mainly to adjust and stopped the medium in the water and gas line .Its working temperature ≤ 80 ℃.
 
Connection type: wafer, flange, lug
 
According to the different forms of the valve’s body, Butterfly valve have three connection type . All of them the part are same while the body structure is different. .The final choice of valve’s type always according to the user’s requirement and valve’s working conditions.
 
Main parts: body, disc , stem, seat, bushing, O-ring, pin (always used in centerline butterfly valve)
 
Those are basic fitting, assembled out of the butterfly valve without drive, In order to assemble a normal valve ,Need to add an actuator .
 
Actuator : hand lever, worm gear, electric, pneumatic(single-acting pneumatic, double-acting pneumatic)  and so on .
 
Bolting is required to connect the actuator with the valve’s body.Handle butterfly valve need two bolts, worm gear, electric, pneumatic actuator butterfly valve use four bolts.Above DN700  to use need eight bolts.
 
Common body material:
Cast iron: the United States generally known as CI or A126, Europe called GG25, China called HT200 or HT250, due to quality and price reasons, the cast iron production gradually reduced in recent years . 
 
Ductile iron: the United States said DI or A395, Europe said GGG40 or GGG50, China called QT450-10. Its quality is better than gray cast iron, the price is not much difference, which instead of gray cast iron to become the most common butterfly valve body material.
 
SS304: also known as CF8. The main content is OCr18Ni9. Belongs to stainless steel.
 
SS316: also known as CF8M. The main content is 1Cr18Ni9Mo2. The Corrosion resistance is better  than SS304 .
 
316L: also known as CF3M. Content is OCr17Ni14Mo2. It’s corrosion resistance better than 316. But the price is expensive.
 
Common disc material:
 
Ductile iron: must be nickel-plated.
 
SS304: also known as CF8. The main content is OCr18Ni9. Belongs to stainless steel.
 
SS316: also known as CF8M. The main content is 1Cr18Ni9Mo2. Its corrosion resistance is better than SS304 
 
Aluminum bronze: AL-B2. Also known as C954.
 
Composite Material: In order to increase corrosion resistance It’s painted sprayed nylon or plastic bag on the valve outside.
 
Common stem material:
45 #: also known as carbon steel shaft, It’s can’t  resistant corrosion. Generally used in non-corrosive media.
SS410: Stainless steel . Composition is 1Cr13. Usually  used in butterfly valve .
SS416: Composition is Y1Cr13. A little different from SS410. The price almost same .
SS304 / SS316: good corrosion resistance, the relative price is relatively high.
SS431: strength is the best. If the pressure exceeds the PN20, you must use the SS431 shaft. The price is higher than the SS410 material.
Monel shaft: copper and nickel alloys. anti-corrosion  But  highest  price.
 
Common seat material:
Buna-N rubber: also known as NBR or BUAN-N, the main medium is oil, the normal working temperature at about 80 degrees. The maximum temperature lower than  100 degrees.
EPDM: The main medium is water, or oil-free medium. Widely use. Which can used in  120 degrees . Normal working temperature is 100 degrees.
EPDM rubber seat  include: wear-resistant EPDM and drinking water EPDM, wear-resistant EPDM suitable in switching frequently working conditions. Drinking water EPDM manufacturers must  obtained drinking water Certification which suitable for drinking water pipe installation.
Polytetrafluoro ethylene: also known as PTFE. PTFE. Can used in high temperature, corrosion-resistant features . Working temperature is 120 degrees. Also can be used up to 140 degrees.
Fluorous rubber: also known as VITON. Its can used in high temperature. Working  temperature at 180 degrees. Also can be used up to 200 degrees.
 
Common bushing material:
Lubricating bronze: The price is a little  high,but less using .
Teflon/PTFE : stable performance, affordable price
 
O-ring: general NBR or EPDM .Also can used FPM according to the using condition. 
 
Pin: In order to ensure the sealing performance, the pins are tapered, the taper rate is 1:50, the material is SS410, SS304 or SS316 also can be selected .
 
Common actuator material
Hand lever :  1. General use Magang material. Also known as malleable cast iron . Chinese name is KTH350. Widely use range . affordable price
 
2.Aluminum handle. Also known as stamping handle. More beautiful. The price is a little  high.
 
worm gear / electric / pneumatic actuator : choosed according to the specific needs of the user .
Generally 6 "(DN150mm) or above 6" (DN150mm) of  butterfly valve, it is recommended to use the worm gear / electric / pneumatic actuator .
 
Related valve’s standard :
1.Design standard: refers to the design criteria of the valve. Mainly refers to the thickness of the valve and the length of the structure.
The design standard of butterfly valve include:the Chinese standard: GB13927-92. USA: API609. German standard: DIN3202.
2 structure  length: The length of the structure refers to the length between the two sealing surfaces of the valve,Face to Face. General  the structural length of the butterfly valve standard is: API609 / DIN3202-K1 / EN558.
 
3 connecting flange. Also called side flange. Refers to the installed valve used on pipeline flange connection size. Different countries have different standard of the flange. The connection flange is the basic requirement of the valve. The first thing to determine the connecting flange standard. Every  country flange using as follows:
 
China standard: national standard PN10/PN16
 
Germany standard: as same as the national standard. That is DIN
 
American standard: ANSI B16.1 or 125#. 150#. ANSI B16.5  
British standard: BS4504.   as same as German standard.
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