Butterfly Valves FAQ and Repair
I. What does a butterfly valve look like? What are its characteristics?
Butterfly valves have very distinct characteristics:
They are small, lightweight, and have a simple structure, making them suitable even for large diameters.
They flow very smoothly through water and materials, with strong flow capacity.
During operation, the valve plate and seat experience significant wear.
Except for triple-eccentric butterfly valves, it's generally difficult to achieve a perfectly tight, zero-leakage seal.
They have shearing force during operation, making them suitable for media containing mud, particles, and filamentous materials.
II. Some butterfly valve repair photos
III. Real repair case
Specifications: 8-inch / 150 lb / Valve plate 316 stainless steel / Valve seat RPTFE / Brand: ZZJG
Problem: The valve seat pressure plate and soft-seal valve seat are completely missing; the valve plate sealing surface is scratched and damaged. Repair is required to meet ANSI VI leakage standards.
Why did it break down like this?
It had been used for too long; the valve plate was damaged by compression and impacts, and the seals were also missing.
How was it repaired?
First, polish and grind the valve plate sealing surface until smooth.
Close the valve plate completely and accurately measure the valve body and valve plate dimensions.
Calculate the self-aligning clearance, compression, and angle.
Draw a CAD drawing and remake the valve seat and pressure plate.
Install and test; it meets all standards.
Worktime: 7 days
IV. What are the most common problems with butterfly valves? How to repair them?
1. Damaged sealing surface/seals
Metal seal + elastic component: Mostly die-stamped; prioritize buying parts from the original manufacturer. You can also have a professional factory measure and customize, but it's more expensive. If all else fails, you can modify the structure and buy parts locally.
Metal seal + non-elastic component: Generally, this is for triple-eccentric, heavy-duty butterfly valves. You need machining molds; welding and machining repairs are quite difficult.
Soft seal: Buy seals directly from the original manufacturer or have them custom-made by a professional factory.
Seals that cannot be replaced: High machining difficulty; it's recommended to repair by welding and then manually.
2. Triple eccentric butterfly valve is broken.
This valve requires high precision, precise calculations, and specialized mold machining, making repair quite difficult. Don't try to fix it yourself.
3. Valve stem stuck (rust, media ingress, bent)
Minor stuck: Local heating can loosen the stuck area, then disassemble and clean it.
Moderate stuck: Forcefully remove it, remeasure and machine the valve stem, and repair the stuffing box. Generally, a boring machine is required.
Severely stuck: The old valve stem must be cut and destroyed, and the valve stem and damaged parts must be redesigned and machined. A boring machine is also required.
ZZJG Valve provides the above information on butterfly valves FAQ and repair. If you want to know more about butterfly valves FAQ and repair, please contact us via WhatsApp or email.
Butterfly valves have very distinct characteristics:
They are small, lightweight, and have a simple structure, making them suitable even for large diameters.
They flow very smoothly through water and materials, with strong flow capacity.
During operation, the valve plate and seat experience significant wear.
Except for triple-eccentric butterfly valves, it's generally difficult to achieve a perfectly tight, zero-leakage seal.
They have shearing force during operation, making them suitable for media containing mud, particles, and filamentous materials.
II. Some butterfly valve repair photos
III. Real repair case
Specifications: 8-inch / 150 lb / Valve plate 316 stainless steel / Valve seat RPTFE / Brand: ZZJG
Problem: The valve seat pressure plate and soft-seal valve seat are completely missing; the valve plate sealing surface is scratched and damaged. Repair is required to meet ANSI VI leakage standards.
Why did it break down like this?
It had been used for too long; the valve plate was damaged by compression and impacts, and the seals were also missing.
How was it repaired?
First, polish and grind the valve plate sealing surface until smooth.
Close the valve plate completely and accurately measure the valve body and valve plate dimensions.
Calculate the self-aligning clearance, compression, and angle.
Draw a CAD drawing and remake the valve seat and pressure plate.
Install and test; it meets all standards.
Worktime: 7 days
IV. What are the most common problems with butterfly valves? How to repair them?
1. Damaged sealing surface/seals
Metal seal + elastic component: Mostly die-stamped; prioritize buying parts from the original manufacturer. You can also have a professional factory measure and customize, but it's more expensive. If all else fails, you can modify the structure and buy parts locally.
Metal seal + non-elastic component: Generally, this is for triple-eccentric, heavy-duty butterfly valves. You need machining molds; welding and machining repairs are quite difficult.
Soft seal: Buy seals directly from the original manufacturer or have them custom-made by a professional factory.
Seals that cannot be replaced: High machining difficulty; it's recommended to repair by welding and then manually.
2. Triple eccentric butterfly valve is broken.
This valve requires high precision, precise calculations, and specialized mold machining, making repair quite difficult. Don't try to fix it yourself.
3. Valve stem stuck (rust, media ingress, bent)
Minor stuck: Local heating can loosen the stuck area, then disassemble and clean it.
Moderate stuck: Forcefully remove it, remeasure and machine the valve stem, and repair the stuffing box. Generally, a boring machine is required.
Severely stuck: The old valve stem must be cut and destroyed, and the valve stem and damaged parts must be redesigned and machined. A boring machine is also required.
ZZJG Valve provides the above information on butterfly valves FAQ and repair. If you want to know more about butterfly valves FAQ and repair, please contact us via WhatsApp or email.
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