Pressure Gauge Failure: The Top Eight Causes
The humble pressure gauge is an important but often-undervalued component that plays a vital role in reducing the risk of accidents, so when a gauge fails, it can have serious consequences. A failed gauge may lead to the loss of your ability to detect an issue before a major safety incident happens.
Even smaller accidents can lead to injury and downtime. An accident will lead to a delay while the problem is fixed, and could put employees in harm’s way. This is why it is important to be aware of the risk of gauge failure and how it can be prevented. Here are the main eight reasons why pressure gauges fail, and what you can do to avoid a failure.
Extremes of temperature can have a significant effect on pressure gauges. the effect on gauge
reading is ±0.4% per 10°C change in temperature from ambient.
If high process temperatures are a factor, recommend that either the gauge is mounted remotely and impulse tubing is used to connect the gauge to the process line. That’s why if extremes of temperature are a factor in your operations, it is best to choose pressure gauges that are designed to cope with the environment. These are often equipped with seals that can ensure isolation from media that is too cold or hot.
2. Overpressure/sudden depressurisation
All instruments are designed to withstand a minimum of 115% overload.
It is normal for process media to flow through a system of pipes at high pressure, but when valves are opened or closed and pumps switched on or off, media can surge in the pipe. This causes a dramatic spike in pressure that pegs the pointer against the stop pin inside the gauge. If left unaddressed, this can lead to bending of the pointer and damage to the Bourdon tube or the sensing element, which can, in turn, lead to a rupture and failure of the gauge
To avoid the risk of overpressure issues, one solution is to opt for gauges that have a pressure range greater than the designed overpressure. You can also consider having overload stops built into the instrument that will allow up to 300% overload, alternatively overload protection valves or snubbers can be retrospectively fitted to protect against pressure spikes. Gauges can also be protected against sudden depressurisation or exposure to vacuum in a system by the use of vacuum stops and a free zero.
3. Mechanical vibration
There have been several studies revealing that vibration can be a major factor in gauge failure. Not only does mechanical vibration make it difficult to read a gauge, but it can cause incremental damage that may nudge the pointer in the gauge off the zero mark. Different gauges will be able to withstand different levels of vibration. Often in high vibration scenarios. To protect against vibration options available include, viscous damped movement and or liquid-filled gauge
It is often the case that the process media used in a facility is corrosive. This can have a negative effect on pressure gauges, which can prematurely fail if they are not made from the appropriate material. Where corrosion is likely to be a factor, pressure gauges can either be manufactured from compatible materials or the gauge can be fitted with a diaphragm seal utilising either a lining or exotic material compatible with the process. This extends the life cycle of the instrument and also acts as a containment device against loss of medium.
Misuse includes both mishandling and misapplication. Gauges
can be damaged by a range of factors, including accidental damage sustained during inspections. Misapplication occurs when a gauge has been incorrectly installed or the wrong type of gauge has been used. Regular training of employees on the correct way to handle gauges can help limit the risk of mishandling while taking expert advice on the installation of pressure gauges can help you to avoid misapplication.
When media cycles quickly through a pressure gauge, this can produce recurrent pressure spikes, which are known as pulsation, and which can cause significant damage to the gauge over time. A loose or fluttering pointer can often be a sign of pulsation damage and if not addressed, eventually internal parts can fail completely, rendering the gauge essentially useless. Fitting a viscous damped movement in conjunction with a restrictor in the socket of the gauge is one way to prevent this form of damage.
This can be a major issue in pressure gauges, particularly when the process media is liable to congeal or crystallize. If a gauge becomes clogged, it can effectively freeze, rendering it unable to display the correct pressure, creating potentially dangerous situations. A diaphragm seal utilising a large internal bore will negate this issue, it can also be used in conjunction with a flushing port (purge port) which can be used to flush the diaphragm to prevent build-up and clogging of the inlet. Flush face diaphragms are also available in order to reduce crevices.
It is common for industrial processes to incorporate high-pressure steam, but this can damage the components of the gauge if it seeps inside, leading to the potential of gauge failure. If high-pressure steam is a factor in your operations, the instrument should always be of safety pattern construction. The use of a syphon or impulse tubing should be considered. This helps to minimize the impact of high-pressure steam.
One fairly simple change that can help you to manage your pressure gauges is to ensure the standardization of your gauges. This not only makes it easier and cheaper to ensure a proper supply of replacement parts, but it also removes the risk of employees fitting the wrong replacement part.
Operations that are concerned about the state of their pressure gauges can also call on MIEPL to carry out a full pressure gauge audit. A complete evaluation can include:
A visual check on the pressure gauges in the facility
Diagnosis of potential threats and risks
The creation of an overall plan to address the issues identified
An audit of the stockroom inventory to ensure that all replacement parts are correct
Help you to create processes that will avoid the risk of misapplication and mishandling
Help to coordinate employee training to promote proper pressure gauge management including repair, recalibration and recertification.
It is not surprising, given the huge complexity of overseeing the operations of a facility process plant, that relatively small components like pressure gauge can be overlooked or disregarded. But the pressure gauge plays a hugely important role in any production facility, helping to reduce downtime, promote safety, and ultimately to boost profits. Taking the time to ensure that your pressure gauges
are operating at their optimum level can be one of the best business investments you will make.