FAQ

How is a rupture disk (bursting disc) manufactured?

A “trial-and-error” manufacturing process is employed to establish the final design that will satisfy a customer’s specific requirements. During the manufacturing process, skilled technicians adjust design variables that may include material of construction, material thickness, crown height, score depth (if a scored disk) and often, material thermal treatment (annealing or stress relieving) to determine the best combination of variables that will satisfy the stated requirements. Many test breaks are performed during the manufacturing process to validate the design.

How do I know which is the best rupture disk (bursting disc) design for my particular application?

Unless you are rupture disk (bursting disc) “literate” we recommend you contact our factory-trained sales representatives or the factory for assistance. We will require complete operating conditions the disk will be exposed to in order to recommend the proper rupture disk (bursting disc) design. ZOOK offers “no charge” engineering and technical seminars to educated personnel on rupture disk (bursting disc) technology and disk selection.

Can I operate under vacuum?

In general, most tension-loaded or conventional style disks require a vacuum support to withstand full vacuum. Reverse buckling disks will “withstand” or (resist) full vacuum without the use of a vacuum support. Always consult the factory for specific model number confirmation.

Will ZOOK help me size a disk for my application?

ZOOK does not take responsibility for sizing a customer’s application. It is the responsibility of the customer to determine the parameters for correct disk sizing.

Do you have any technical information on Klinger®-Sil gaskets?

Klinger®-Sil is a compressed fiber, non-asbestos gasket material. ZOOK uses Klinger®-Sil C-4401 for standard alert sensor gasket material and type ARD disks.

Can you cross-reference a competitor’s product?

Most competitors’ products can be identified and cross-referenced by the nomenclature used for the various types of disks and holders.

At what temperature do you specify the rupture disk (bursting disc)?

Disks should be specified at the temperature at which the disk will be exposed to when it is required to rupture. ZOOK does elevated temperature testing to ensure the rupture disks (bursting discs) they provide will rupture at the customer’s specified pressure/temperature request.

When do I require ASME “UD” stamping of my rupture disk (bursting disc)?

Since January 01, 1999 Jurisdictions that require ASME Code compliance require UD certified rupture disks (bursting discs) regardless of the application.

Does a Teflon® liner add to the burst pressure of the disk?

This depends on the type of rupture disk (bursting disc) and pressure.

What is a temperature shield?

A temperature shield is a non pressure retaining perforated metal component installed between the disk and the process that can reduce the temperature at the disk as much as 50%. The shield is typically installed between standard flanges as far below the disk as possible and has limited dampening characteristics that can reduce the magnitude of system pressure spikes.

The “process management system” portion of OSHA 29 CFR 1910.119 requires appropriate personnel to be trained in the proper installation, inspection, and operation of plant equipment. Due to typical turnover, how can we ensure our mechanics and instrument personnel are properly trained for rupture disks (bursting discs)?

ZOOK has a training specialist who conducts “on site” training of plant personnel who are involved with the selection, installation, and use of rupture disks. The training fully satisfies the requirements of OSHA 29 CFR 1910.119. Certificates of satisfactory completion are provided to attendees for training files.

I have an application, which seems to “blow” disks too often. Is there something I am doing wrong which would cause the disk to “blow”?

Certainly the condition of the disk and its proper installation may influence disk service life but quite commonly, the disk is being exposed to pressures that exceed the “maximum operating pressure” of the disk. Some disks are designed to be exposed to system pressures no more than 50% of the marked burst pressure of the disk. Others may be exposed to 90% of their marked burst pressure with only negligible metal fatigue. Exposing a disk to pressures in excess of their designed “maximum operating pressure” (expressed as a percent of the marked burst pressure) can dramatically reduce service life. Should you believe you are not getting the service life you need from your rupture disk (bursting disc), we would be pleased for the opportunity to discuss your service environment and perhaps, recommend a disk design that would offer you longer service. Remember that proper installation can also significantly influence disk service life.

I’ve been asked to reduce our inventory of rupture disks (bursting discs). Right now we have so many types, materials, and burst pressures; I don’t know where to start. Does ZOOK have any recommendations?

In many instances disks for a variety of applications may be consolidated. Certainly size is a prime consideration. Secondly, material of construction is important. In many instances, two disk applications currently manufactured from Alloy 600 and Alloy 400 may be satisfied with a common disk manufactured from Alloy 600. A disk such as the ZOOK  RA series can be used in both liquid and vapor service reducing the need for disks of two different descriptions for different service conditions. ZOOK would be pleased to offer assistance.

We always get into “Discussions” about the proper procedure for isolating relief valves with rupture disks. What is the “right” way?

We recommend the practices defined by the ASME Code and API. The rupture disk (bursting disc) and the relief valve should be “close coupled” (No intervening spool piece). The disk and relief valve should be set at the same nominal pressures. The cavity between the rupture disk (bursting disc) and the relief valve must be monitored to ensure there is no pressure in the cavity. Since rupture disks (bursting discs) are differential pressure devices, any pressure downstream of the rupture disk (bursting disc) is considered a “back pressure” and will prevent the disk from opening at its marked burst pressure. See specific details on the Code or request assistance from your local ZOOK factory-trained sales representative.

What is a “reverse-buckling” rupture disk?

Also called a “compression-loaded” rupture disk (bursting disc), a “reverse-buckling” rupture disk (bursting disc) is one which is installed with the crown of the disk (convex side) facing the system pressure.

What are the advantages of reverse-buckling rupture disks (bursting discs)?

Be careful, not all reverse buckling rupture disk (bursting disc) designs are equal; accordingly the user should verify the attributes of the specific disk design to insure it will provide the service life and safety required.

Typically reverse-buckling rupture disks (bursting discs) are significantly more service-durable than forward-acting (tension-loaded) rupture disks (bursting discs). Most have a maximum operating pressure of 90% (can be exposed to system pressure up to 90% of their marked burst pressure). Almost all reverse-buckling rupture disks (bursting discs) are designed for non-fragmentation which makes them most ideally suited for isolation of relief valves from the process environment.

What is a pre-torqued holder?

Modern rupture disk (bursting disc) holders are designed with integral pre-torque bolts that allow the disk to be installed in the convenience of the maintenance or instrument shop prior to field installation with the recommended torque load to ensure proper engagement of the “bite” type seal. Once assembled, the device can be installed in the field where the additional load of the companion flange bolting provides for complete functionality of the device.

In addition, pre-torque assemblies allow for the removal of the assembly from the piping system for inspection and reinstallation without disturbing the seal integrity. Fluoropolmer coated bolts are standard to provide corrosion resistance and much lower frictional coefficient.

May a rupture disk (bursting disc) be used as a primary relief device?

Yes. The ASME Code recognizes the use of a rupture disk (bursting disc) as a primary relief device.[/accordion-item]

Yes. Depending upon the style of disk selected, a wide variety of sensors (and sensor monitors!) are available. Additionally, ZOOK manufactures a special “leak detector sensor” to assist in determining if a rupture disk (bursting disc) is leaking due to improper installation, corrosion, or erosion.

How do I install my sensor?

Every order is supplied with Installation Instructions for proper installation. In general, the sensor is placed between the outlet flange of the holder and the downstream companion flange. For specific instructions please request the Installation Instructions for the specific product type.

Why should I isolate relief valves from the process environment with a rupture disk (bursting disc)?

Several answers apply to this question. First, should the rupture disk (bursting disc) protecting a relief valve from the process not rupture from exposure to excess process pressures, the relief valve is maintained in a clean, pristine condition. Valve maintenance costs are, accordingly, dramatically reduced. Second, isolation of relief valves with rupture disks (bursting discs) is environmentally smart. The “bubble tight seal” of a rupture disk (bursting disc) prevents valve leak, seep, weep, and chatter.

What is a “tell-tale” indicator?

When a rupture disk (bursting disc) is used to isolate a relief valve from the process environment, the ASME Code requires the cavity between the rupture disk (bursting disc) and the valve seat to be monitored. Since a rupture disk (bursting disc) is a “differential” pressure relief device, any pressure in the cavity between the rupture disk (bursting disc) and the relief valve seat will act to elevate the burst pressure of the rupture disk (bursting disc). A “tell-tale” assembly is a method to satisfy this Code requirement. Other methods may also be used to fulfill this requirement. (See ASME Code)

Are all rupture disks (bursting discs) suited for both gas (vapor) and liquid service?

NO! Consult ZOOK catalog literature or contact your local factory-trained sales representative for specific service applications for which disks may be used. ZOOK does offer a broad scope of rupture disks (bursting discs) which are suitable to both gas and liquid applications.

Should a rupture disk (bursting disc) be “rated” at the MAWP of my system?

This answer to this question is really at the Discretion of the user. A rupture disk (bursting disc) specified at the system MAWP will typically provide the longest possible service of that particular style of disk (since its marked burst pressure is as far from the system pressure as possible). Some prefer an extra “margin of safety” between the marked burst pressure of the rupture disk and the MAWP and request the disk to be rated less than the MAWP.

What is Section VIII of the ASME Code?

Division I, Section VIII of the ASME Code is the portion of the ASME Code which most commonly applies to rupture disk (bursting disk) applications, sizing, selection, and installation for unfired pressure vessels. Other portions of the Code also address rupture disk (bursting disc) use in more diverse applications (such as nuclear applications).

May the disk I am ordering be ASME/UD stamped?

ZOOK does perform testing to confirm flow coefficients of our products to obtain ASME/UD certification from The National Board. Please contact ZOOK sales support for a specific style, size, and specified operating media to determine if a particular disk has UD certification.

Is there a charge for burst certificates, mill certificates, or certificates of conformance?

For disks, the burst certificate, mill certificate, or certificate of conformance are free. There is a charge for mill certificates for holders and ASME certifications.

What information do you need from me to reorder a rupture disk (bursting disc)?

A previous “Lot Number.”

Where will I find my Lot Number?

You can locate your Lot Number on an old invoice or on the tag of the old rupture disk you are replacing.

Can you give me a lot number description?

Lot numbers allow ZOOK to duplicate previous order specification. ZOOK lot numbers are composed of 6 digits followed by a sequential number. Very old lot numbers are composed of 4 digits. Contact the representative in your area, or you may call the factory for lot number identification.

I need to send in a disk for evaluation, how do I do that?

Call ZOOK and request an RMA authorization number. Make sure you provide ZOOK the lot number, product type, quantity to be returned, contact name and phone number, etc. requested on paperwork along with the authorization number requested from ZOOK. You will send the product back with the appropriate paperwork. Upon evaluation, ZOOK will provide a written report free of charge.

What is the status of my RMA?

Provide the return material ticket number when inquiring about your RMA. If you do not have the correct RMA number, provide the ZOOK lot number and we can locate the order in our system.

Can you improve the delivery date on my order?

ZOOK understands that sometimes customers need expedited delivery for a particular order. Our Emergency Service Support Department is ready to handle emergency orders. Since all rupture disks (bursting discs) are custom-manufactured, there is a cost associated with this service. Therefore, it is imperative for both the customer and ZOOK to understand what is needed and when. This helps coordinate Sales, Manufacturing and Shipping to get the disk into the customer’s hands exactly as requested and prevents costly mistakes to the customer and ZOOK. Contact the channel partner in your area, or call us direct.