Monthly Archives: December 2015

CHESTERTON was requested by a large chipboard & laminated-chipboard manufacturer customer to provide seal solution for their new laminating press.

The press is a state-of-the-art technology short stroke, high speed press what laminates the melamine paper to the surface of the chipboard by high pressure and high temperature.

The press has 12 pcs of main press cylinders with down-stroke rams. Diameter of the rams is 420 mm each.

The OEM seal solution;

• had unexpectedly short life time (18 months)
• the rubber and cotton particles from the traditional CHEVRON sets – traveling through the hydraulic system – plugged the main filter causing shut-downs and production losses

Facts;

• the oil filters had to be replaced in every 2 – 3 months
• replacement work of the filters took 1 hour
• production loss in 1 hour is approx 400 m2 of laminated board ( in total 6 x 400 m2 = 2.400 m2)
• production loss caused by seal replacement works in total 21.000 m2

One of challenges was to provide a solution that can be installed without the complete disassembling of the cylinders saving production time.

The 11K EZ Stack Pack Split was chosen based on the operation conditions of the press (in addition 9K Anti-Extrusion Ring and Spacer).

In 3 steps 4 seal sets were replaced while finally the rest 8 seal sets were installed during one night (10 hours) as a campaign to eliminate the further production losses.

Installation dates;

• May 2005 – 2 sets ( still in operation – 42 months )
• June 2005 – 2 sets ( still in operation – 41 months )
• July 2005 – 8 sets ( still in operation – 40 months )

Results;

• Zero leakage (no oil loss) since May 2005
• No one shut down to replace oil filters
• No production loss cause by plugging of filters
• No production loss caused by seal replacements
• Doubled life time of the seal sets

• Reduced maintenance costs
• Improved reliability & production
• Easy installation and quick to repair
• No gland adjustments (maintenance free)
• Safer working environment

In the refining section of fibre board manufacturing, several screw feeding presses such as the moistening screw, plug screw feeder, pre-heater discharge screws and the refiner infeed  screw, are used for conveying the chips through the process.

The sealing of these screws is often done through a standard stuffing box arrangement with compression packing. This sealing arrangement often suffers from short packing life that result in steam leakages.

These steam leakages present a safety issue and cause subsequent failure of the bearings because of moisture.

Mechanical seals are usually considered as the solution to the packing problems of the feeding screws. But as these screws are difficult and time consuming to disassemble, standard mechanical seals are not a practical solution for mills.

Chesterton innovative split mechanical seals provide the sealing performance of mechanical seal while avoiding costly downtime of the equipment. Installation and repair can be done quick and easy on site.

The 14K split flexible lip restriction bushing installed with the split seal, protects the seal from abrasion from chips and fibers allowing optimal sealing performance and longest time between repairs.

• Reduced maintenance costs
• Improved reliability
• Easy and quick to repair
• No equipment teardown
• No gland adjustments
• Safer working environment

The challenge with sealing pneumatically actuated control valves is to find the right balance between sealing performance and stem friction control. A higher packing stress would naturally lead to better sealing performance but at the same time lead to higher friction on the valve stem.

High stem friction is an issue particularly in pneumati-cally actuated valves due to the combination of a relatively low actuation force in combination with a need for high actuation accuracy.

A refinery in Slovakia was looking for a sealing solution for their Sulfuric Acid Fisher Control Valves that would give them the right sealing performance in combination with good actuator response.

The Leakage of sulfuric acid was causing environmental, health and safety and operational issues.

The Fisher OEM sealing solution was a PTFE wedge type packing which did not give satisfying results. The total number of valves was 20. The temperature of the sulfuric acid solution is 70-100°

The valves were sealed with the 1724E sealing solution consisting of die formed 1724 PTFE rings with a 5150 Live Loading system. The installation was done back in 2009 and the valves are still in operation. Style 1724E gives extremely well low emission results and has as well the lowest friction of all the available Chesterton packings.

Chesterton products used in the solution: Style 1724E Control Valve Sealing System

Makes valves compliant to stringent international emission legislation

• Provides extremely low valve stem friction

The main steam isolation, start up and non-return valves at a fossil generating station were blowing out the packing twice a year during start-ups and shutdowns.

The costs associated with these failures were numerous;

• On line leak injection cost €1000+ per valve
• Forced outages were caused because the valves could not function. (Costing in the millions of €)
• Steam leaks would burn the grease out of the motor actuator, average cost of repair €8000+
• Valve repair after on line injection average cost was between € 10000 – 20000 each valve

Chesterton’s Valve Live Loading Sealing Program eliminated all of the challenges listed.

Some of the valves have been successfully sealed for a decade or more with zero failures using our valve program and technology.

Major safety and repair issues were eliminated because of reliable sealing of high pressure steam, 250 – 310 bar.

The savings are in the € 80,000 +, however the asset preservation and reliability aspects of the program are the real winning combination.

• Chesterton can extend the MTBR on severe service valves with their proven sealing systems
• Chesterton Valve Live Loading is designed to reduce leakage, increase safety and extend the life time of the valve
• Chesterton guarantees that valves stay leak free for a period of at least 5 years with their valve live loading systems

Chesterton products used in this solution: Valve Live Loading

Application Details

• Equipment Main Steam Valves
• Media Steam Pressure 250‐350 bar

The previous sealing system was made out of an old Chesterton 5600+5300 set as following:

• 3 x 5300 rings + 2 x 5600 rings in the bottom of the stuffing box
• Lantern ring
• Back-up set consisting of 1 x 5300 sealing ring + 2 x 5600 rings

This sealing system was failing every 2-6 months. There were some OEM springs installed on the studs.

The Customer asked Chesterton for immediate support in February 2008. He agreed with the Complete Live Loading solution with carbon bushing, three 5300 sealing rings and three to four 1600 end rings, with 6 Live Loading assemblies for 24 mm studs. The first two valves are packed in April 2008.

By the end of 2008, none failed and the customer standardized all the eight critical valves. In 2013 the valves are still running leak free.

Products used in this solution: Valve Liveloading 5150, Die Formed ring 5300, 1600

• Chesterton can extend the MTBR on severe service valves with their proven sealing systems.
• Chesterton Valve Live Loading is designed to reduce leakage and extend the life time of the valve.
• Chesterton guarantees that valves stay leak free for a period of at least 5 years with their valve live loading systems

ROI

Previous solution (OEM Solution)
Total Cost (every 3 months): 2.800 € + production loss

Chesterton Solution:
Chesterton Live Loading: 3.500 € NO Production Loss

Total Cost (20 months): 3.500 €
Total for eight (8) valves: 128.800 € + production

Application/Equipment:

• Main Heater
• Quantity 8 Valves
• Stem diametre 70mm
• M24x6 Studs
• Medium steam was outputting at Temperature: +450°C (300 bar)