What happened to the valves when the German olefin producer had a major shut-down at their ethylene cracker?
German olefin producer had a major shut-down at their ethylene cracker in September 2012 and some valves were sent for service to Neles’ service center in Horgau, Germany. This was already the second time that this customer sent their valves for service to our valve factory. Are these valves not working well? Let’s see what our German colleague Raimar Hellwig, Business Manager of butterfly valves has to say about this:
Raimar: "Actually the valves are working very well and they do this already for more than 10 years. To mention one example: despite the very challenging fluid of cracked hydrocarbons, all the ethylene cracker valves which are installed until today provide very safe and reliable operation without any known case of jamming during opening or closing. This service was part of the scheduled shut-down for the ethylene cracker that takes place every 6 years. This is the typical frequency that these kind of valves should be maintained and spare parts can be changed."
Ethylene cracker transfer line valve being serviced at Neles service center in Horgau, Germany.
During the operation the reliability of the valve is crucially important. An unscheduled need for maintenance on the TLVs before the shut-down is mostly unwanted because of the safety risks, production loss or other operational costs.
The valve type we are talking about is Neles’ ethylene cracker valves, type Mapabloc™. These valves are the main valves in the transfer line (TLV), the pipeline which is transferring the cracked gas from the cracking furnace to the plant. First valves in DN1600 and DN700 as transfer line valve were installed already in 2001. First service of the transfer line valves was in 2006. Because of the outstanding performance of the valves, one more DN1600 TLV was ordered and installed at that time.
During the ethylene cracker shutdown in September 2012 the time frame for the service was quite short. We understood that we need to do our best to send the valves back in time, since every day of shut-down is generating costs without production. During re-installation, all processes have to comply and work together like a clockwork. Just like six years ago, all people from service, machining and manufacturing, worked together. Everything went very smoothly. Within eleven days two DN1600 (64”) and two DN700 (28”) Mapabloc rotary valves were maintained in the service center and sent back to the customer cracker again.
Schedule for the service.
But why is it needed to send these valves to the service center? Two major things are important: the on-time performance as mentioned above and also the repeatable reliability of the valves.
Regarding the first point, our Neles service people are very well experienced with all the steps and processes which are important. Already in advance, when the valves were still installed in the pipe, all preparations were done, and possible spare parts were checked and placed ready in stock. It means that the job would have been completed safely even if some unforeseen work would have come up, e.g erosion of internal parts due to heavy coke particles.
Secondly, to maintain ethylene cracker valves does indeed mean to ensure again six more years (or even more) of safe and reliable operation with the guarantee to our customer that the valve performance remains like it was on the first day – in this case as ten years ago. When leaving the service center, each Mapabloc valve is subjected to an intense series of tests to prove the cycling and the absolute tightness of the double block and bleed sealing.
This will ensure that the customer can ease up and rely on Mapabloc rotary valves will perform as they should be during the cracker furnaces periodical decoking also during the next six or more years until we will see them again in the factory and service center in Horgau, Germany.
Many things changed since 2001 when these valves were shipped the first time to be installed in this ethylene cracker. Some may have the feeling that the times are rushing faster and faster and more things are just build to last for short time and to be replaced by some new and fancy product. But ones every six years we are happy to see that the good old solid machines are making a difference.
Written by Sari Aronen. For additional information on the topic, please contact ville.kahkonen@valmet.com
Text originally published in 2012, and slightly updated in April 2022, due to the company name change to Valmet.
