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HX the story

Greater demands calls for action

In 2011 Stafsjö was faced with a request from a worldwide known OEM supplier with strong foundation within the Pulp and Paper Industry. They wanted a technically fast and reliable valve capable of operating within a broad range of pressures, pulp concentrations and temperatures. The development team at Stafsjö got down to work and the story of the 20 bar/300 psi rated HX began.

– We have experienced this development during many years: the production volume at pulp and paper mills across the globe are increased, new mills are being built capable of achieving new record production volumes and old plants are being converted or upgraded. As a knife gate valve supplier Stafsjö represents a part of a great machinery equipment, but rather than let the grass grow under our feet we want to support further development within the sector with product solutions to realize new efficiency and production goals, says Oskar Rüdow, Product and Engineering Manager at Stafsjö.

Stafsjö works in close collaboration with its customers to maximize customer benefit. During the course of 2011, the team at Stafsjö developed a prototype that following a large number of in-house test runs, was transferred to OEM suppliers’ own test facility for more advanced endurance tests. 

– It was a great feeling when the prototype tests proved successful. The development took off thereafter. To date, we have supplied the high pressure HX in sizes ranging from DN 200 all the way up to DN 900 in stainless steel and also in high alloy materials such as SMO 254, titanium and duplex, says Oskar. 

The potential area of use has increased over time. Now the valve is also used within other areas and sectors that Stafsjö had not initially anticipated. But it is within the pulp and paper sector where the application scope of HX is at its greatest – now and most likely also in the future. 


The Stafsjö HX knife gate valve ensures batch digester isolation during pulp stock production

In chemical pulping, some fiber lines operate with a continuous cooking process while others operate in batch cooking. In the batch cooking process, the wood chips and cooking liquor are heated with steam under high pressure. Once the cooking process is completed, the digester is emptied through a blow valve at the digester bottom, and onward to a blow tank. During blowdown, the process equipment is subjected to high velocity, pressure, abrasion and temperature, as well as severe vibration. The batch digesters discharge to a common header, which is connected to a blow tank further downstream. When one digester is out of service for blow valve repair or other maintenance, the chemical pulp mill normally shuts down all digesters in series to ensure the work can be carried out safely. This results in a major loss of pulp production.

Stafsjö’s severe service HX valve has successfully been installed as a maintenance block for complete isolation in batch digester clusters. The HX valves are placed downstream of the blow valve, but before the common pipe or header leading to the blow tank. During regular batch cooking process, Stafsjö’s HX valves are locked open. When a digester needs to be shut down for maintenance or inspection, the HX is closed and locked, allowing that particular digester to be depressurized and the blow valve removed, or blow down piping disengaged, while the rest of the digesters continues to process pulp as normal. Stafsjö’s HX provides 100 % bi-directional isolation, to prevent any back flow reaching the shut-down area. Downtime is minimized, maintenance work can be performed safely and the production levels can remain steady because the other digesters can continue to feed the mill with pulp stock while the one digester is being maintained. The Stafsjö HX valve is built to withstand the unique pressure, temperature, chemical, abrasion and vibration extremes associated with this application.

Further information
Please feel free to contact Stafsjö on or on +46 11 39 31 00 for additional information on knife gate valves for the Pulp and Paper industry.

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Further info on the HX valve...

With Stafsjö’s valves Firefly protects valuable installations worldwide

When it comes to industrial fire protection systems, reliability is essential. On constant standby during long periods, the system should be able to respond immediately and extinguish possible ignition sources to prevent fires and dust explosions. In the Firefly solution, Stafsjö’s valves have an important duty. 

For more than 30 years ago, Firefly decided to use Stafsjö’s valves in their fire protection systems. Firefly develops its high safety solutions in Hammarby Sjöstad and exports them throughout the world. Almost 80 % of its output is sold outside Sweden.

– Demand is high and growing all the time. For our customers, fire protection is extremely important. It must not go wrong. Therefore, we must also be able to rely on our subcontractors. In our system, the valve itself is a critical component, says Kristoffer Tannerfeldt, Risk Manager at Firefly.

Firefly’s industrial business area covers customers within the food industry who deal with cereals, cocoa and sugar, but also board, diaper and pellet manufacturers, all of whom handle raw materials that represent high ignition hazards. Major investments and other financial assets are at stake. And the fact that people can be injured and even killed as a result of industrial fires and dust explosions makes the need for reliable spark and industrial fire protection systems even greater.  

Within the system developed by Firefly, there are  detectors that identifies dangerous particles (ignition sources) in the process flow. When a detector recognizes any kind of deviation, the control unit sends a signal to the isolation valve, which closes before the dangerous particles have passed through. Extinguish media can be water, but CO2 gas is also commonly used to reduce oxygen level quickly to prevent fires from starting.

– In a fraction of a second, the flow must be blocked and the process closed completely. Therefore, our systems must be on constant standby, inactive for long periods, and ready to be activated, explains Kristoffer.

– We have more than 30 years’ experience of Stafsjö’s valves. They are robust, reliable, and deliver performance when required. It is a reliable product that provides the quality we and our customers value. With a closed knife gate, we can prevent fires and dust explosions and thereby enhance levels of fire safety at our customers.

Firefly uses Stafsjö’s HG isolation valve with through-going gate for reliable shut-off performance independent of pressure direction. Its ability to cut through static media columns also serve its purpose well. Superior flow characteristics enable it to act as a part of the pipe system without affecting the process flow. Stainless steel metal seats extend the service life and offers low friction to achieve ultra-fast isolation time. Sometimes the valve is also supported by a pressure tank to speed up the shut-off time.  

With a strong workforce of 80 dedicated people, Firefly has made a name for itself over the years. Clients are now made up by users in Europe, North America, Asia and South America, and increase in numbers every year. 

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Durable valves in a tough environment

Presenting a tougher environment than that of many other processes, with low pH values and abrasive media, the processing of food, slaughterhouse and kitchen waste at Linköping’s biogas plant generates two highly demanded products - biogas and bio-fertilizer. We are talking about the achievement of a sustainable society in practice. 

If it’s going to work, the process equipment must be capable to withstand tough strains, says Håkan Widerström, Maintenance Co-ordinator at Tekniska verken in Linköping, one of Sweden’s leading producers of biogas with its own in-house development department that willingly shares its experiences:

– The anaerobic digestion process tear heavily on the process equipment. It literally eats valves and pumps. One could say our environment is similar to a combination of pulp production and mining and its mineral processing. It is therefore important that we work with the right components from start. 

Valves must close properly and remain tightly sealed. Even a micro leak can have devastating consequences. In instances where reverse flow occurs or the wrong material finds its way into the process, you have to terminate it and start all over again – with a severe production disturbance and non delivery as a consequence. 

Håkan Widerström strongly believes you can count on a knife gate valve from Stafsjö to fulfil its duty.

– It’s designed and developed to meet challenging conditions, and he rest assured the flow is blocked when the valve is closed. Thereby the system also becomes easier to monitor and manage. Working with the right equipment not only minimizes maintenance work, it also provides a sense of security. We can focus on other aspects and quality assure the process and production chain, says Håkan.

Tekniska verken mostly uses Stafsjö’s stainless steel MV valve that efficiently manages food waste with its cutting knife-like shut-off. The MV is also available in a nodular iron version for more pH neutral processes. The stainless steel XV valve is used where there is a need to ensure full tightness regardless of pressure direction. 

A factor that determines the quality is the sorting of the household waste. Glass shards, bottle caps and eggshells are often included but add nothing positive. When the waste is placed in tanks this complicates the digestion process resulting in extensive maintenance as an outcome. With the help of a high density cleaner, which is also widely used in pulp and paper mills to clean the pulp, waste is separated from the biomass by a vortex and high density particles are collected in a reject chamber where the HG serves as the inlet valve and the robust RKO as the outlet valve.

The demand for biogas is high. Many municipalities and transport companies in Sweden are required to operate fossil free. Today, sustainability is a crucial criterion when an entrepreneur’s services are procured. This means biogas is relevant and timely right. On the one hand, household waste is disposed of, and on the other, digested to become fuel and organic fertilizer material for agriculture.

– From a sustainability perspective, it also feels right to use components that will last over time. We should not be part of the ’throw-away society’ without thinking about a cycle and conducting a life cycle analysis of the materials and resources we use, says Håkan.

Tekniska Verken in Linköping is a technology leader within its field and hold a competence that is widely demanded. Its strength also lies in the fact that they managed to prove to the market that the business can be run on a commercial basis.

Further information
Please feel free to contact Stafsjö on or on +46 11 39 31 00 for additional information on knife gate valves for the biogas industry.

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Tough specification demands behind record-breaking valve

China is not only a huge and important market, it is also hold an industry requiring large components. Stafsjö were consulted with a challenge, which one solved and qualified Stafsjö into the group of suppliers to one of the world’s largest pulp and paper mills. “We are breaking new ground” says Stafsjö’s KAM Pulp and Paper in China Su Chuansheng.

The blow tank tower is 32 meters high and the pressure is obviously very high. The bottom valve should be able to hold this tight and to operate through highly concentrated pulp. The environment is aggressive and exposed. 

– This was a demanding project, explains Su Chuansheng.

– There was no knife gate valve in such a large dimension for a duty like this, as far as we know. We went through the whole process together with the end customer and machine supplier and made some detailed calculations. The outcome was a success, adds Su.

The end customer is a giant within the Chinese business world and one of the largest producers within the pulp and paper industry. Their catalogue of demands is clear. Growth and productivity are in focus, but not at the expense of economic, social and environmental sustainable values. It wants to be a model playing a leading role in the industry.

To achieve near-zero emission rates and minimize consumption of resources, the pulp producer carefully selects its technical solutions.  High quality at a reasonable price. To meet this challenge, Stafsjö was forced to make every effort. The result was one of the largest valves in the company’s history, tailored to meet requirements from the customer.

–The valves have gradually increased in size over the last years. It was not so long ago that we manufactured a couple of DN 1200 (48”) valves. Then we made some DN 1400 (56”) for Brazil and now we have built a DN 1600 (64”) valve. But then again, we have the competence and expertise amongst our design engineers and a strong team in the workshop, says Marcelo Alvarez, Product Manager for Stafsjö in China. 

So it was a ’real piece’ – a customized MV valve – that left Stafsjö’s factory for its eastward bound train journey. Back in China, work is now underway to deal with new enquiries and projects.  

Stafsjö is a strong and well-known knife gate brand in China. With an office in the country for over twenty years, it is easier to monitor market demands and there are still many sectors with a strong growth. With this reference, the company will be able to further strengthen its position within Pulp and Paper industry.

– We have the skills and experience which allows customers to consult with us to find the adaptations for various processes. Our strength is also that we keep delivery times, even if they are tight sometimes, says Su.

Further information
Please feel free to contact Stafsjö on or on +46 11 39 31 00 for any questions on valve solutions for the Pulp and Paper industry.

If you are you interested in the knife gate solutions for pulp related processes in China, please feel free to contact our sister company Ebro Armaturen:

Su Chuansheng, KAM Pulp and Paper, 

Experience how we contribute to cleaner water

At the new Pålslund wastewater treatment plant in Värnamo municipality, Sweden, the knife gate valve WB14 are used to shut-off and to keep tight during long periods of time. No less than 230 pcs have been installed.

Now you can experience the shut-off performance online on

Stafsjö valves provide cleaner water

Clean water. The production is full running at the new Pålslund waste water treatment plant in Värnamo municipality, Sweden. One of the most modern around the Baltic Sea. This is a unique project where suppliers are subject to the highest demands. No less than 230 of Stafsjö’s knife gate valves can be found in the facility. Each and every one from Stafsjö, that scores the highest rating for its flexibility.

Demands placed on sewage treatment plants continue to increase. But so too does the necessity of returning the water used by households and industry to nature.  A purity of the highest order must be attained, enabling our ecosystem of microorganisms residing in watercourses to continue working. This is a responsibility that we all share.

Quality in focus
 - We quickly realized that it is better and easier to build a new plant than to patch up our old installations, especially if should meet the demands required of us. Here we have a system that is designed with functions that we can easily control and manage. Pålslund is unique, says Ulf Nilsson, Water & Drainage engineer at Värnamo municipality.

This set high demands on all equipment. From a mechanical point of view, it is a large and complex project. The specification requirements are clear. The valves used must be fully up to the job. This is of particular importance because the sewage treatment plant in Värnamo is controlled and managed on-line.

Value for money
At every turn a Stafsjö valve can be seen, often several per section. Yet their implementation is a science in itself. A completely new pump station has been built down in the centre of Värnamo. With its impressive capacity, 1,600 cubic meters of waste water per hour pumped 40 vertical metres over a distance of 6 km up to the waste water treatment plant located just outside the town.

- Stafsjö is a natural choice for us, says Håkan Wennerhag at the construction company, Malmberg.

- In terms of quality, these are excellent products and I cannot find anything ‘comparable’. Stafsjö may not be the cheapest but they always meet the highest standards and have a support organisation that is fast and steps up to the mark. These are affordable, reasonably-priced valves for the money. 

Sizeable installations
Down in the pumping station, 10 metres below ground, a huge hall can be found. Here it is difficult to even embrace the tubes with open arms. The valves from Stafsjö are also sizeable.

- One might think that we have exaggerated. But the last plant lasted for 40 years. Here we have planned for a longer life span and the increasingly high demands placed on purification. This is why we have equipped the plant with components, control systems, piping, pumps and valves that meet these requirements, says Ulf Nilsson.

Those municipalities and operators which do not meet the increasingly stringent treatment requirements for nitrogen risk large fines and penalties. 

Smooth operator
Leachate from the Stomsjö landfill and waste dump is also transferred to the Pålslund wastewater treatment plant. Three additional municipalities in the region, which up until now have had their own treatment plants, will be connected to the plant in the near future.
In the planning phase the dialogue with suppliers, as well as establishment of parameters such as price, quality, deliverability and performance, are all crucial.

- For me, Stafsjö is synonymous with safe and secure delivery, says Håkan Wennerhag at Malmberg Water. We wanted and needed 230 units, fully lugged type, bolted from both sides, for the sewage treatment plant in Värnamo. Stafsjö was out in front. We got a really good service and they did not let us down at any time.

Serve as a model
A number of situations arose during the construction period. When changes were made on the pipe sizing, Stafsjö managed to squeeze in additional orders in the middle of their production schedule, just to ensure they fulfilled the supply obligations.

- We are very satisfied. Whenever we needed any customizations of any components they, in principle, came with the return delivery. They are as committed to the final delivery as we are. So this is not the last time we will contract Stafsjö, adds Håkan Wennerhag who also took valves from Stafsjö with him to the sewage treatment plants in St: Petersburg, Russia, and Klaipeda in Lithuania, both in need of upgrading.

Värnamo municipality with the Pålslund facility will serve as a model. This is a plant that represents a major step forward for the technology in waste water treatment.

Further information
Please feel free to contact Stafsjö on or on +46 11 39 31 00 for any questions on valve solutions for water and waste water.

Stafsjö steaming ahead in the energy sector

In Alabama, there are 24 power plants. One of them is James H. Miller, Jr. Electric Generating Plant outside Birmingham. It's a real big one that produces over 2800 MW with its four generators. Here plays Stafsjö a central role. With over 300 knife gate valves.

Sustainability is a key word for Alabama Power, Southern Company. Environmental responsibility permeates everything the company does. Working in the energy sector becomes then a challenge, especially if the power plant is fired with coal. Air emissions must be minimized to zero.

"The goal is to reduce fly ash release. It is an important health and safety factor to ensure  good air quality for the plant personnel” says Mason Romans, Stafsjö specialist on Ebro Armaturen USA and adds:

"With Stafsjö products we were able to present a solution that has worked like clockwork since installation. Our customized solution yielded reliability. We have not had any reports of malfunctions since installations began. 

Sustainability for the energy company is not just about managing strict emission requirements, but also to dispose of and to use the fly ash. With proper control of the process you also get a quality suitable for concrete production.

In all production there are residues and wastes. So also here. Fly ash is fine powder found in plant exhaust gases exiting the boiler and it is removed before the gas is discharged to atmosphere. The fly ash is generally collected in electrostatic precipitator hoppers and then fed into a conveying system. The isolating valve under a ash hopper is normally in open position and it have to close on a static column of ash, without using extreme force or any other unsafe practises. 

Handling of fly ash is difficult. It is very fine-grained and harmful. Before the installation of Stafsjö valves, the plant used conventional knife gate valves. Fine ash collecting in cavities of these valves, caused routine malfunctions. 

"The production line was pretty annoyed. They wanted to get a better solution. In Stafsjö’s portfolio we have the HG series which was the perfect solution. Now we have 77 HG valves in place in each unit. A total of four units becomes 308 valves. And both parties are quite satisfied, "says Bill Lollar, Territory Manager on Severe Service Specialist, Inc (Triple S).

“The HG series is an O ported knife gate with a through-going gate designed for static column applications. This valve series has excellent flow characteristic and no area in the bore where the ash can get packed preventing the valve from operating.  Any ash in the valve body is naturally cleared through normal operation.”, says Mason Romans.

Mason Romans also emphasizes that the Stafsjö HG enables operators to open and close the valves easily, without having to resort to some unsafe practices. Through simple maintenance and reliable performance they have achieved a higher level of safety and air quality at an affordable cost for the facility.

"Competition among manufacturers of knife gate valves is razor sharp. We have many domestic manufacturers, a lot from Asia and a few from Europe. But I would say they have started talking about Stafsjö in the US as a reliable quality brand with a flexible product range and the ability to customize solutions, emphasizes Bill Lollar. 

James H. Miller, Jr. Electric Generating Plant is outside of Birmingham, a city of nearly 225,000 inhabitants. Birmingham is a hub for business in the American South with everything from steel and telecoms to the financial sector and a number of universities. There is also the 18-story headquarters of Alabama Power.

“You know, with Stafsjö we have a track record back to 1666”, summarizes Mr. Lollar.

Further information
Please feel free to contact Stafsjö on or on +46 11 39 31 00 for any questions on valve solutions for ash handling.

If you are you interested in the knife gate solutions for ash handling in the USA, please feel free to contact Mason Romans on Ebro Armaturen USA on

Stafsjö enabled the world record

The region west of Sao Paulo in Brazil has become the world’s largest producer of cellulose. With annual production of approximately 1.5 million tons of bleached eucalyptus market pulp, Eldorado Brazil’s new Três Lagoas mill is currently the largest single-line pulp mill in the world. And further expansions are planned.

The mill uses Best Available Technology and the mandate is clear: develop a large-scale, state-of-the art plant with high productivity and low conversion cost. Meeting al sustainability requirements. 

“For technical solutions and highly respected quality Stafsjö was a natural choice, say chief engineer Vesa Romppanen from Andritz, the key supplier for the new pulp line. He specified and purchased the Stafsjö valve type “MV DN 1400/56” for high density bleach stock and tower isolation. “We needed a tailor made valve says Vesa, and Andritz know from past experience that we can rely on the team at Stafsjö. Together we found the solution for this project, a customized 3,5 tonnes MV valve with purge ports close to the seat, capable to handle really high pulp concentrations. This is a huge project with many challenges, extreme pressures and large amounts of pulp and water per second”.

Eldorado started up on December 6, 2012. On time. Everything has worked as a clock works since. Vesa Romppanen has not heard any remarks or complaints. On the contrary. The first shipment of pulp left for its final destination to Mobile, Alabama in January 2013. The plant reached maximum capacity for first time in March 2013. A year after Eldorado set wold record three times in a week producing around 5,000 tons in a single day.

The output, from planted eucalyptus forests, a 100 per cent renewable source, is exported to paper producing markets in South America, North America, Europe and Asia, to produce everything from toilet paper to paper towels, napkins and wrapping paper.

The company plans a two-phase expansion that will create the largest pulp mill in the world. The 2017 phase will double the mill's capacity and the 2021 phase will increase total production capacity to 5 million tons. The facility is also contributing to the local population, providing jobs for about 25,000 people and is an important contribution to Brazilian exports.

Further information
Please feel free to contact Stafsjö on or on +46 11 39 31 00 for any questions on customized solutions for pulp and paper applications.

If you are you interested in the knife gate solutions for pulp and paper applications in Finland, please feel free to contact our sales partner Tecalemit Flow Oy and Marcus Finne on or +358 29 006 280.