Showing posts with label Fike. Show all posts
Showing posts with label Fike. Show all posts

Wednesday, October 31, 2018

Overpressure Protection Devices

Fluid pressure exerts force on any surface area it contacts, as described by the formula F = PA. One practical consequence of this fact is that process vessels and pipelines may catastrophically burst if subjected to excessive fluid pressure. If subjected to excessive vacuum, some vessels and piping may implode (collapse in on themselves). Not only do these potential failures pose operational problems, but they may also pose severe safety and environmental hazards, especially if the process fluid in question is toxic, flammable, or both.

Special safety devices exist to help prevent such unfortunately events from occurring, among them being rupture disks, relief valves, and safety valves. The following subsections describe each of these protective devices and their intended operation. In a P&ID, rupture disks and relief valves are represented by the following symbols:
Overpressure Protection Devices

A rupture disk acts like an electrical fuse for overpressure protection: when the burst pressure is exceeded, the disk ruptures to let fluids escape through it. Safety and relief valves work like self-resetting circuit breakers: they open to relieve pressure, then re-close to seal the process system once more.

Two common causes of process overpressure are piping blockages and overheating caused by fires. Although it may sound ridiculous, a number of fatal industrial accidents have been caused by something as simple as shut block valves that should have been left open. When fluid cannot escape a process vessel, the pumping forces may exceed the burst rating of the vessel, causing catastrophic failure. Fires may also cause overpressure conditions, owing to the expansion of process fluids inside sealed vessels. Overpressure protection devices play a crucial role in such scenarios, venting process fluid so as to avoid bursting the vessel. It should be mentioned that these two causes of overpressure may have vastly differing protection requirements: the required flow rate of exiting fluid to safely limit pressure may be far greater in a “fire case” than it is for a “blockage case,” which means overpressure protection devices sized for the latter may be insufficient to protect against the former.

Overpressure protection device selection is a task restricted to the domain of process safety engineers. Instrument technicians may be involved in the installation and maintenance of overpressure protection devices, but only a qualified and licensed engineer should decide which specific device(s) to use for a particular process system.

For more information on overpressure protection devices, contact Flow-Tech by visiting https://flowtechonline.com or by calling 410-666-3200 in MD or 804-752-3450 in VA.


Reprinted from "Lessons In Industrial Instrumentation" by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.

Saturday, April 28, 2018

Flameless Explosion Venting

Explosion test
Explosion test without flameless vent.
(Courtesy of Fike)
In the event of a plant explosion, the flames and dust exiting the process vessel threaten a plants personnel, equipment and property. In a normal venting situation, an explosion is freely discharged, with threatening dusts and flames exiting the process vessel. The dust and flame are then channeled down vent ducts and ultimately outside the building. The ductwork has disadvantages though, and indoor plant installations cannot be protected by explosion vents alone.

Flameless venting is highly suited for indoor applications and, used in in combination with explosion vents, can extinguish the flame from the vented explosion without the use of expensive ducting, limitations to equipment location, or more costly explosion protection.  Flameless explosion venting protects people and equipment from flames and dust by using a flame absorber with a mesh filter to rapidly and efficiently cool and extinguish the flames immediately.
Explosion test
Explosion test with flameless vent.
(Courtesy of Fike)

Flameless venting is a viable alternative to ducting.  Since indoor venting is not permitted, the designer has to select between vent ducting and flameless venting, and sometimes flameless explosion venting is the only alternative.

Advantage of Flameless Venting:
  • Eliminates need for expensive ducts
  • Enhanced venting efficiency over venting with ductwork
  • Virtually maintenance free
Explosion venting system designers must take design standards into consideration in order to ensure that the calculated relief area and selected venting devices are compliant with local codes and laws.

Flameless venting must consider venting efficiency and incorporate it in the overall design. The venting efficiency factors of the venting and flameless venting devices are manufacturer product specific, can be application specific and should be used in accordance with the manufacturers’ recommendations only.

It is also critical to discuss your explosion venting application with an applications expert. Gaining their  knowledge and experience can literally mean the difference between success and disaster.

Monday, October 9, 2017

5 Myths of Dust Explosion Propagation

Fike explosion testing
Dust explosion propagation testing at Fike labs.
Abstracted from
"Dust Explosion Propagation: Myths and Realities"
by Fike Corporation


The unfortunate propensity of dust explosions to destroy entire facilities and claim lives has been reported in numerous past incidents.

Powder handling processes are often comprised of interconnected enclosures and equipment. Flame and pressure resulting from a dust explosion can therefore propagate through piping, across galleries, and reach other pieces of equipment or enclosures, leading to extensive damage.

While the ability of dust explosions to propagate has been widely recognized, some misconceptions lead to the false sense of security that explosion isolation is not required.

This post will enumerate, illustrate and unravel 5 common myths about explosion propagation. Download the full Fike White Paper here, or read it in full at the bottom of this post.

Myth #1: A large amount of dust is needed for an explosion to propagate.

Dust explosions do not need large amounts of fuel to propagate.

A 1 mm layer can create a dust explosion hazard in a typical room. The explosion only needed a 1/100 inch layer of dust on the ground to fully propagate.

Myth #2: A dust explosion starting in a vented vessel cannot propagate through connected pipes.

It is a common belief that protecting an enclosure, by means of venting or suppression, will affect explosion propagation in such a manner that no explosion isolation is needed at all. 

Although venting protects a vessel from the high pressures generated by an explosion, it does not necessarily prevent the explosion from being propagated through piping into other vessels.

Myth #3: A dust explosion cannot propagate against process flow. 

An argument also often heard is that a dust explosion cannot propagate against pneumatic process flow. 

An explosion is capable of traveling both with and against process flow, even over long distances.

Myth #4: A dust explosion weakens as it propagates.

Literature includes numerous discussions about explosion behavior in interconnected vessels. 

Experimental evidence has shown that explosions not only propagate, but become increasingly more damaging.

Myth #5: Small diameter pipes do not support dust explosion propagation.

Dust explosion propagation in small pipes has always been a controversial topic. The primary argument being that flame propagation is challenged due to heat loss to the pipe walls.

While conditions for dust explosions to propagate in relatively small diameter pipes are not yet fully established, their ability to propagate has been clearly demonstrated by several researchers.

Contact Flow-Tech with any questions regarding explosion protection testing, isolation valves, vents and systems at http://www.flowtechonline.com or call 410-666-3200.

Friday, August 18, 2017

Explosion and Fire at Chemical Plant Case Study

Fire and explosion testing to mitigate risk.
Fire and explosion testing to mitigate risk. (Fike)
Industrial accidents, whether minor or catastrophic, can serve as sources of learning when analyzed and studied. Operators, owners, and technicians involved with industrial chemical operations have a degree of moral, ethical, and legal responsibility to conduct work in a reasonably and predictably safe manner without endangering personnel, property, or the environment.

Part of a diligent safety culture should include reviewing industrial accidents at other facilities. There is much to learn from these unfortunate events, even when they happen in an industry that may seem somewhat removed from our own.

The U.S. Chemical Safety Board, or CSB, is an independent federal agency that investigates industrial chemical accidents. Below, find one of their video reenactments and analysis of an explosion that occurred at a Louisiana chemical processing plant in 2013. A portion of the reenactment shows how a few seemingly innocuous oversights can combine with other unrecognized conditions that result in a major conflagration.

For more information on industrial plant safety products that mitigate fire and explosion risk,  contact Flow-Tech at 410-666-3200 in Maryland, or 804-752-3450 in Virginia

Tuesday, January 31, 2017

Safety and Performance Through Proper Installation and Maintenance of Rupture Discs

rupture discs
Increase safety with proper installation
and maintenance of rupture discs.
Rupture discs are fixed setpoint devices designed to provide failsafe performance in venting gases or liquids in the case of excessive pressure. The precision made and certified disc is contained within a holder specially designed for the disc and to facilitate proper inspection and maintenance.

An integral part of the inclusion of a safety device in a process system is the manner in which it is installed. Documented product performance, upon which the user is depending, is predicated upon installation in a manner which duplicates the rating condition. Varying from the manufacturer's installation procedure or instructions can have an impact on the performance of almost any process measurement and control product, but adherence to procedure is especially important when safety devices are concerned. The video below demonstrates the proper procedure for installing Fike rupture discs.

Fike provides certified rupture discs to meet all applications for process industries including isolating pressure relief valves from corrosive materials, reducing involuntary emissions, insuring pressure relief in critical applications, rupture discs for sanitary/pharmaceutical processes.

Share your over-pressure safety requirements with a product specialist and select from the complete line of cost-effective rupture discs, holders and custom pressure relief devices which are compliant with global code regulations and designed to meet or exceed industry requirements for performance, reliability and quality.

Wednesday, August 31, 2016

Rupture Disc Sizing Technical Bulletin

rupture disc
Rupture disc (Fike)
The objective of this bulletin is to provide detailed guidance for sizing rupture discs using standard methodologies found in ASME Section VIII Div. 1, API RP520, and Crane TP-410. To assist in the sizing process, contact Flow-Tech at 410-666-3200 for help.

Overpressure Allowance

When sizing pressure relief devices, the Code defines the maximum pressure that may build up in the pressure vessel while the device is relieving. This pressure varies depending on the application of the device. The following table defines the various overpressure allowances.

Rupture Disc Sizing Methodologies

There are 3 basic methodologies for sizing rupture disc devices:
  • Coefficient of Discharge Method (KD) — The KD is the coefficient of discharge that is applied to the theoretical flow rate to arrive at a rated flow rate for simple systems.
  • Resistance to Flow Method (KR) — The KR represents the velocity head loss due to the rupture disc device. This head loss is included in the overall system loss calculations to determine the size of the relief system.
  • Combination Capacity Method — When a rupture disc device is installed in combination with a pressure relief valve, the valve capacity is derated by a default value of 0.9 or a tested value for the disc/valve combination. See technical bulletin TB8101 for specific application requirements when using rupture disc devices in combination with PRVs.

Monday, July 25, 2016

Installing Sanitary Rupture Discs

Sanitary Rupture Disc
Sanitary Rupture Disc
by Fike
Rupture discs are designed to provide instantaneous pressure relief at a predefined pressure and temperature. Installation is an important consideration that can affect the performance of a ruptured disk. Installation instructions are included with all ruptured disk shipments. These instructions should be followed carefully and completely.

Remember to locate the rupture disc word will have sufficient clearance to operate unhindered. The rupture disc should be vented to a safe area where people and equipment are not at risk as a system discharge can be hazardous, or cause injury. The piping near the rupture disc should be braced to absorb shock caused by the opening a ruptured disk. A danger sign should be placed in a conspicuous location near the zone of potential danger. Keep the danger sign clean and unobstructed for ease of viewing.

Fike sanitary ruptured discs are designed for use with standard sanitary ferrule's and clamps. There are a variety of sanitary ferrule standards used in industry including, but not limited to, Tri-Clover with standard clamp, and also high-pressure clamp DIN 32676, ISO 2852 and NovAseptic NA Connect.

To install a new ruptured disc, remove the ruptured ruptured disc from its piping. Please use caution as a ruptured disk may have sharp edges. Remove clamp, and separate the ferrule components. If this is an existing installation, it is important at this point to do a visual inspection of the ferrule. Inspect them for nicks, scratches, dents, gouges and galling. Before installing a new ruptured disc into the ferrule, clean the seat area with the solvent compatible with your media.

When unpacking the new ruptured disc it should be handled carefully. Visually inspect the rupture disc for damage. Read the complete information contained on the ruptured disc tag. Verify that the disk size, type, pressure, and temperature are correct for your system. After verifying that you have the correct rupture disc, inspect the silicon, Viton and EPDM gasket position, and ensure that the gasket ID is centered on the dome the rupture disc. Then place the rupture disc directly into the ferrule’s, with the flow arrow on the ruptured disc tag pointing in the same direction as the required flow. For the Teflon and J1500 gaskets, carefully place both at the gasket halves on the rupture disc, so that they interlock around the outside diameter of the rupture disc, so that the ruptured disc tag extends through the notches in the gasket haves. Place the rupture disc into the ferrule’s with the flow arrow on the ruptured disc tag pointing in the same direction as the required flow.

Install the clamp around the ferrule’s, so the gap between the two clamp haves is centered and equal on the ruptured disc tag. Apply the recommended torque to the clamp at this time. Specifications can be found in the written installation and maintenance instructions. Whenever possible it is recommended to install sanitary rupture discs between two ferrule spool pieces. Using this approach can help prevent any unintentional stress or damage to the disk during installation. Assembly can take place at a workbench, rather than at the installation location, where conditions could be less than ideal, greatly reducing the possibility assembly errors. This practice is suitable for standard ferrule installations utilizing Tri-Clover with standard clamp, and also high-pressure clamp DIN 3267 and ISO 2852. Fike realizes that conditions do not always allow for this, so caution should be exercised when installing rupture discs directly between two ferrule’s.

As part of the new 3A Standard 60-01, certified sanitary ruptured discs are suitable for a one-time use, or single installation only. Depending on the cleanability of components in your process, rupture disks can be cleaned or steamed in place if the process allows. Avoid any high pressure stream of cleaning agent from being directly focused on the ruptured disc, as this could cause damage. If ruptured discs are removed from the process for any reason, they must be replaced in order to remain compliant with 3A Standard 60-01. 3A certified rupture discs will be marked both with the 3A symbol and one-time installation statement. An optional feature for the sanitary rupture disc would be the integral burst indicator, which provides instantaneous notification of rupture disk activation.

Fike ruptured discs and ferrule's come in many sizes and types. A common requirement of all designs is proper handling and installation. This explanation assumes installation is done under ideal circumstances. We realize that the location of your particular ruptured disc may not be ideal, however when these steps and written instructions are followed as closely as possible, the performance and service life of your rupture disc may be enhanced. As always contact technical support or your local Fike representative if you have any questions or need any assistance.

Thursday, February 18, 2016

The Concept of Explosion Protection Venting

Explosion venting products
Explosion venting products
(courtesy of Fike)
When a spark or other ignition source ignites particulate in a vessel a fireball develops as material burns in grows at an exponential pace. The pressure front expands as the fireball grows reaching the explosion vent. The explosion vent opens at a specified pressure, limiting the stress on the vessel on allowing it to maintain structural integrity, while also releasing the pressure and allowing the fireball to vent into a safe area outside the facility.

Alternatively, when the process can not be vented safely outside, the explosion vent opens and directs the fireball into a flameless venting device. the flames are extinguished as they pass through the flame arresting screens allowing pressure release, but preventing dangerous flames from entering the work area protecting personnel and preventing secondary explosions. It is also necessary to isolate the deflagration, preventing the transmission the flame into interconnected vessels.

During a deflagration, the pressure wave from the explosion reaches the detector connected to the explosion protection control panel, which processes 4,000 data points per second. The system alarms at a preset pressure level and sends an activation signal to the isolation devices.

The system opens a rupture disk on isolation container that uses 500 psi of nitrogen to drive suppressant into the ductwork, providing a chemical isolation barrier that prevents the propagation of the explosion. the system maintains a history of the event for future reference.

Simultaneously, the gas cartridge actuator drives the piston on the isolation valve, closing the slide gate, and provides mechanical isolation which prevents the propagation of the explosion through the duct work too interconnected vessels.

Sunday, January 31, 2016

Explosion Detection and Suppression Systems

explosion detection system
Explosion detection system (by Fike)
A typical explosion detection sequence begins when a spark or other ignition source ignites particulate in a vessel. The resulting deflagration grows at an exponential pace as the material burns. The pressure front preceding the deflagration expands, reaching the pressure detector connected to the explosion protection control panel, which processes 4,000 data points per second. The system alarms at a preset pressure level, and activates the gas cartridge actuators on the suppression and isolation devices. The system maintains a history event for future reference.

The gas cartridge actuator drives the piston on the isolation valve, closing the slide gate and provides mechanical isolation which prevents the propagation of the explosion through the duct work to interconnected vessels. The actuator opens a rupture disk on the suppressor bottle, that uses nitrogen pressurized to 900 PSI to drive suppressant into the vessel, filling the entire cavity and extinguishing the advancing deflagration.

It is also necessary to isolate the deflagration, preventing the transmission of the flame into interconnected vessels. The system simultaneously opens a rupture disk on an isolation container that uses 500 PSI of nitrogen to drive suppressant into the ductwork, providing a chemical isolation barrier that prevents the propagation of the explosion. Fike’s explosion protection system effectively saves lives and property from explosion damage.