Pressure Relief and Pressure Safety

Can I fit an OsecoElfab rupture disc into another manufacturer’s holder?

No. As specified by the Pressure Equipment Directive, one manufacture’s rupture disc cannot be placed into another manufacture’s rupture disc holder. Installing products in alternative holders will invalidate the CE marking, warranty and insurance.

My discs are bursting too often, what could be the problem be?

A number of factors come in to play which can affect the performance of the disc. Possible issues could include the following:

  • Deteriorating condition of the disc
  • Incorrect installation of the disc and/or holder
  • The installation could be exceeding the specified maximum operating ratio
  • Damage to the disc

We are happy to assist you investigating the cause of unwanted bursting.

Can a rupture disc be used for purposes other than pressure relief?

Yes, you can use discs as pressure switches, for example, to enable the controlled activation of propellant systems by bursting and therefore allowing the two mediums to mix.

What different types of disc are available?

There are two main categories of disc designs:

  • Forward acting (tensile loaded)
  • Reverse acting (compression loaded)

However, graphite and custom design (OEM) discs are also available.

What size discs are available?

OsecoElfab can supply discs from 1/8” (3mm) up to 32” (800mm) in diameter.

What does ‘working pressure to burst pressure ratio’ mean?

This is the margin between the Maximum Recommended Working Pressure for the disc design and the bottom limit of the burst pressure for the disc.

Do rupture discs replace safety relief valves?

Not always. Increasingly, engineers are using a rupture disc in combination with their traditional valve to enhance the pressure relief solution and achieve the most cost effective explosion protection. Using a rupture disc in addition to a valve means the system benefits from the unique advantages of each individual solution, whilst maintaining a reasonable cost.

Process leakage into the atmosphere is kept to a minimum and valve life is extended by isolating corrosive fluids from internal valve parts. As secondary protection, discs also offer a back up in case of downtime and can enhance the SIL level of the system by adding layers of protection. For safety-critical applications, ‘doubling up’ in this way not only offers greater protection to the infrastructure of a process plant, but also to its people.

How do I know that the holder is fitted into the pipe work in the correct orientation to flow?

OsecoElfab uses a fixed bracket (System-Loc) on the flange inlet, which forces the holder orientation. Each holder is also laser etched with a flow arrow to enable correct installation within the system.

Does OsecoElfab have experience with discs in exotic materials?

Yes. OsecoElfab can manufacture discs in Inconel, Stainless Steel, Nickel, Hastelloy, Tantalum and Monel. The most suitable materials will depend on the specific operating conditions.

Should I keep spare discs?

Yes. Although OsecoElfab offers an industry-best lead time on all products, it is always recommended that you hold spare discs to avoid costly downtime in the event of a burst. If no spares are available and the discs are required immediately, OsecoElfab offers expediting options for emergency orders.

Will a disc withstand back pressure or vacuum?

This depends on the disc design being used. Reverse acting discs such as Opti-Gard will withstand full vacuum without the need for vacuum support, but other designs may require it. Vacuum conditions should be specified with the request for quotation.

Are the disc materials used traceable?

Yes. All disc materials used are traceable and certificates (EN 10204:3.1) can be supplied on request. A nominal charge will be applied.

How do I know I have the correct disc?

The disc will carry a tag that displays all the relevant performance details of the disc. As an absolute minimum the disc will carry the OsecoElfab contract number, which can be traced to the test certificate and checked for the correct specification. Additional markings can be added to the disc tags to identify its unique location within your plant.

How does temperature affect the burst pressure of the disc?

The burst pressure will generally reduce as the temperature increases, and vice versa. However, this is dependent on the disc type and the material used. Please contact us for further information.

How does the rupture disc fit into my system?

Discs are generally fitted into a holder and mounted between pipe flanges. However, they can also have screwed connections or a variety of custom-designed mounting arrangements depending on the particular application. Please refer to the specific installation instructions when fitting. OsecoElfab offers specific training to help your teams understand the importance of correct installation.

How do I know I have the correct holder for the disc?

The disc should be marked with the reference of the holder in which it should be used.

Can I reuse the holder and just replace the disc after it has burst?

In most cases, the holders are reusable and it is only the disc which needs to be replaced. Some applications are more suited to an integral holding device, which is also discarded following a burst.

In the case of a disc with an independent holder and integrated burst detection, only the disc itself has to be replaced after it functions, also eliminating the need to hold stock of detectors.

What is a rupture or bursting disc?

A non re-closing pressure relief device designed to relieve excess over-pressure or vacuum conditions at a pre-determined pressure or temperature.

Do you have to have an excess flow valve on the tell tale indicator assembly when you install a rupture disc under a safety relief valve?

No. ASME only requires you to have the tell tale assembly or pressure switch to monitor the pressure between the disc and safety relief valve. The excess flow valve is to vent very low pressure away from the disc since it's a differential pressure device.

Can your rupture discs be used on Oxygen clean duty?

Discs can be supplied cleaned for use in Oxygen Service at a nominal extra charge.

How do I know when the disc has burst?

Depending on the installation and complexity of the control system, the easiest solution is a rupture disc with integrated burst detection. The disc comes complete with a small magnet, which is pulled away from the sensor upon burst. When installed with the Flo-Tel detection system this gives an open circuit signal.

What information is needed in order to be able to specify the correct disc?

The specification variables to consider when choosing a disc include required burst pressure, burst temperature, nominal bore size, medium, whether it must be a non-fragmenting design, and whether the disc has to withstand full vacuum. There are several other factors as well. As a disc is safety-critical part of the plant equipment, we would always recommend you speak to an OsecoElfab specialist to specify the correct disc for any application.

Order Related Questions

How do I submit my purchase order to OsecoElfab?

Please email your purchase order to orders@osecoelfab.com.

Please use the following address on your PO for the remit to address:

PO Box 504834
St. Louis, MO 63150-4834

Orders cannot be processed unless they are showing the correct remit to address.

How do I know if my purchase order was received?

Orders emailed to orders@osecoelfab.com will receive an automated response indicating your email/inquiry was received.

How do I know when my order has been processed?

Once your order has been processed, you will receive an order acknowledgment via email.

Why aren't the products I ordered in stock and ready to ship today?

At OsecoElfab, we custom build your order to meet the specifications on your purchase order. We do have some select items that have an associated stocking program. For example, see our Explosion Vent Stocking Program. We also have an online store where you can order standard Railcar Discs and Extruder Burst Plugs.

Does OsecoElfab keep discs in stock?

No. Every batch of discs is manufactured specifically to order. However, we do stock a large range of raw materials to minimize leads times.

I can't find what I need in the disc selection guide. Who do I contact for more product info?

To request additional product information, please fill out our online form and an OsecoElfab representative will contact you.

How do I choose a rupture disc for my application?

Our online product search tool and our Disc Selection Guides are great tools to narrow down your product options. If you need additional information, please fill out our online form and an OsecoElfab representative will contact you.

Where can I get the UPS shipment tracking info for my order?

A UPS tracking number is located on your invoice. To track your shipment, please visit the UPS tracking webpage and enter your tracking number.

What do the part codes on each quote mean?

Due to the technical nature of our products, our quotes contain a lot of information about our products. To help you better understand our quotes, below is an example of what some of our part codes symbolize. PLEASE NOTE – this list is not exhaustive and OsecoElfab offers several part-code variations for individual/specific applications. All sizes are in mm.

Category (First three letters of the part code)

  • DSC = Rupture Disc
  • VNT = Explosion Vent
  • ACC = Accessory
  • DET = Detection
  • OE = OEM
  • HLD = Holder


  • HAL = Hastelloy Fluoropolymer Liner
  • HAU = Hastelloy Underlined
  • INL = Inconel Fluoropolymer Liner
  • INU = Inconel Underlined
  • MOL = Monel Fluoropolymer Liner
  • MOU = Monel Underlined
  • NIL = Nickel Fluoropolymer Liner
  • NIU = Nickel Underlined
  • SSL = Stainless Steel Fluoropolymer Liner
  • SSU = Stainless Steel Underlined
  • TAL = Tantalum Fluoropolymer Liner
  • TAU = Tantalum Underlined
  • GRL = Graphite Fluoropolymer Liner
  • GRU = Graphite Underlined

Disc Support (Last three figures of the part code)

  • XXX = Without vacuum support
  • NVS = Non-Opening vacuum support
  • OVS = Open vacuum support
  • 2WS = Two-way burst – same burst pressure both directions
  • 2WD = Two-way burst – different burst pressure in opposite directions
What is the standard warranty on OsecoElfab products shipped from the UK?

OsecoElfab (North Shields site) offers a unique three-year warranty for the high performance reverse-acting rupture disc, Opti-Gard™. For other products, standard warranty is 12 months in service and 18 months in storage.

Why does OsecoElfab require a lead-time for my order?

At OsecoElfab, we provide custom solutions for our customers. We build every lot of parts to suit customers’ special needs as specified on each purchase order. We perform extensive testing on every order to ensure quality and reliability of our products, which takes time. We do offer expediting options for emergency orders.

About OsecoElfab

Who or what is OsecoElfab?

For decades, Oseco and Elfab have been in the business of safety. We’ve designed, built, and innovated products to keep facilities and operations at the highest level of compliance. In 2020, we merged the two companies, Oseco and Elfab, to form a single company, OsecoElfab, with a single Purpose: Protecting Life. Solutions for a safer, cleaner world.

By joining forces like this we can better serve our customers at a global level. We are backed by a global network of partners, and are now at your doorstep, wherever you are in the world, 24/7, 365 days a year.

As we grow together, we will continue to design, build and innovate products to keep facilities and operations at the highest level of compliance. But now, we will do so with the power and force of an entire global team and supply chain. Welcome to OsecoElfab.

Will I still be able to order the same Oseco or Elfab products I currently use?

Yes, we will continue to support and provide all of our current products under the OsecoElfab brand. These parts can be ordered through your original ordering methods and points of contact.

Will I be able to order products in the same way?

In fact, you will have access to an expanded availability of niche product offerings via this website, under the merged OsecoElfab brand’s full product catalogue. You will be able to order products the same way you did before.

Will the paperwork or documentation change?

With our combined brand comes an updated name, logo and visual identity. You will see this on materials such as quotes, invoices and product literature. Product tags and packaging will also be updated.

Can I work with the same point of contact I worked with before the merger?

Yes, your point of contact will remain the same. You will receive correspondence from them on an updated email address from @osecoelfab.com — please make sure they’re updated in your list of contacts and that your company safelists the domain osecoelfab.com. This will ensure you continue to receive our emails as expected.

Will the quality of the products change in any way?

No. OsecoElfab will maintain the same manufacturing locations and processes. Product quality will not change in the slightest.