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Ball valve seat assy: the summit of custom-made

29-10-2018 | The summit of a custom-made product is our ball valve seat assembly. We compile this seat assy of multiple parts of different materials. Often metals are combined with graphite (hard or soft) and plastics. That requires a lot of knowledge, experience and precision. And Ridderflex has it all in-house. We have been a specialist in producing seat assy’s for the valve industry for more than 25 years. For that reason we have many major players in this industry as customers.

Our seat assy’s are used in the marine, offshore, oil and gas and chemical industries, as well as in transport and transshipment (specially for liquid transport and LNG transport).

The ball valve seat assembly

The seat assembly always consists of different parts and is assembled in the following way:

Ball valve seat (front seal)PTFE, PTFE glass, PEEK, PCTFE, carbon graphite.
Ball valve retainerMetals like stainless steel, titanium, nickel aluminium bronze, Hastelloy and Duplex
Ball valve seal (rear seal)PTFE, PTFE glass, PCTFE, PEEK or moulded graphite of both commercial and nuclear grades (99.85% pure).
Possible addition: o-ring or backup ringKalrez ®, FPM/FKM, Devlon, PCTFE.

Custom-made ball valve seat assy’s

We machine all parts of the seat assy in-house. We have extensive machinery, equipped with all the right tools for every solution. In our machine shop, we have specialists for turning metals, carbon graphite and plastics. Machining plastics or carbon graphite are very different specialisms than machining metals. Every plastic or graphite behaves differently under external factors such as temperature and humidity. We guarantee a high level of accuracy in all turning and milling. Depending on the material, we can work to tolerances up to 0.05 mm.

The ball valve seat (front seal), retainer and ball valve seal (rear seal) are ultimately assembled to form one product: the seat assy. Thanks to our years of experience, also of shrinkage and expansion of the different materials, fitting all these loose parts into a seat assembly has become one of our specialties.

Are you curious if we can machine your custom-made seat assembly? Or do you want to make an enquiry? Call +31 (0) 180 46 34 71 or mail to

Also custom-made loose ball valve parts

Ofcourse we can also machine loose custom-made ball valve seats and ball valve seals. We supply amongst others:

Back-up ringsGland packingsTrunnion bearings
Ball support discsKalrez ® o-ringsThrust washers
Chevron setsStem seals

You can find a complete overview of all the parts that we machine for the valve industry on the valve parts page.

Are you interested? Please contact us!  

More custom-made ball valve parts

  • Ring support

    Ring support

    Customised ring supports; endless solid rings as well as split rings. Standard in PTFE or Nylon. Also in PEEK for more critical applications.

  • Chevron set

    Chevron set

    Multi-part and custom-made sealing set. Composed of top rings, middle rings and bottom rings. Supplied in PTFE, PTFE glass (15% or 25%), PTFE carbon or PEEK.

  • Custom-made Kalrez ® o-rings (FFKM)

    Custom-made Kalrez ® o-rings (FFKM)

    We supply Kalrez ® o-rings with a quality guarantee. If desired with a certificate. In any desired dimension.


ISO including co-engineering

Ridderflex complies with international quality management requirements. We are now also certified for co-engineering – our strength – . Read more


Any questions about products or make an enquiry? Simply call us or send us an e-mail. +31 (0) 180 46 34 71