Engineering, Process Safety Management, HSEQ

SPECTACLE BLIND

A spectacle blind is a safety device used in piping systems to isolate a section of pipe. It gets its name because it looks like a pair of spectacles - two metal discs connected by a small piece of metal.

Structure:

• One side is a solid disc (the "blind") - this is used to completely block off flow.
• The other side is a ring (the "spacer") - this allows flow through the pipe.

How it works:

You rotate the spectacle blind depending on whether you want to allow or block the flow:

• If the solid disc is aligned with the pipe, it blocks the flow.
• If the ring is aligned, it allows the flow.

Purpose:

• Used for maintenance, inspection, or shutdowns.
• Provides a visual indication of whether the line is open or closed (since you can see which side is in place).
• Ensures fail-safe flow control, especially in critical or high-pressure systems.

ALARM FLOODS AND PLANT INCIDENTS

Alarm floods and their contribution to industrial incidents can be controlled successfully through all process states

Most of the incident investigations performed by the US Chemical Safety Board (CSB) cite alarm floods as being a significant contributing cause to industrial incidents. In fact, alarm management has become identified as one of the key issues listed on the cover of recent CSB investigation reports. The British-based organisation Engineering Equipment & Materials Users’ Association (EEMUA) came to the same finding in its report from 1999 when it analysed major incidents around the world, including Three Mile Island, Bhopal and Texaco Milford Haven.1 Therefore, the connection of alarm floods to incidents has been well documented for over 12 years. On the whole, industrial progress controlling floods in those 12 years has been nil. Many corporations and plant locations are attempting to do so, but many engineers, including alarm management vendors, do not know what it takes to control floods under all operating conditions. This article shows examples of good alarm management programmes and how they successfully control alarm floods under all operating conditions.

Definition and impact of an alarm flood
An alarm flood has been defined by ANSI/ISA 18.2 as being 10 or more annunciated alarms in any 10-minute period per operator.2 Since ISA issued the 18.2 standard over two years ago, recent OSHA audits have reported that questions on the subject came up during inspections of the plant. An attorney presenting on the topic at the Global Conference on Process Safety 2012 stated that alarms and alarm management were now frequently coming up in audits. It is obvious that OSHA considers the ISA 18.2 standard to be “recognised and generally accepted good engineering practices” (RAGAGEP). As a result, plant managers should be ready to have their alarm performance scrutinised.

Obviously, plants that do not currently meet the ISA 18.2 guidelines under all operating conditions must remediate or face the consequences. The consequences that occur are not only when OSHA audits come to the plant. Consider these items:
• It is commonly reported that 70% of plant incidents occur on startup or shutdown. Shutdown periods are where many alarm floods occur because of the sudden changes from the run state. Could the occurrence of these incidents be caused by one or more critical alarms being “hidden” under the flood of hundreds of alarms typical during shutdown? What about startup after a shutdown where alarm floods have occurred? Until the alarms have cleared, the operators are flying blind without alarms until reactivated. What are the odds of an incident occurring when starting up your plant without alarms to annunciate?
• Are your safety-critical alarms immune to influence by alarm floods? Even special-sounding alarms can be missed when a cacophony of hundreds of flooding alarms are sounding
• What about product quality, plant profitability or equipment damage — have any of these issues suffered when an alarm flood was a significant distraction for the operator while operating the process?
• Has your plant ever performed an incident review to find that a critical alarm was missed? Was personnel action taken against the board operator for poor performance? Was the flood of alarms even considered as a distraction for the board operator?
• Does your plant have any data on how many alarms are missed due to distractions? How many redundant alarms annunciate — alarms with little or no meaning — at your plant? How many loss of containment incidents, injuries or worse can be tracked back to an alarm flood?

From the beginning
Over the last 30 years, the number and frequency of alarms have changed with technology. In the old days of pneumatic controls, installing a new process alarm had significant costs. Since the use of computer-based control systems, new alarms cost nothing. As a result, the number and frequency of alarms has increased significantly over the years. This phenomenon has reached a point where a term was needed to define the experience when numerous alarms are annunciating in a stream — an alarm flood.

Alarms are typically configured for a single operational state — run. Alarm floods typically occur upon a change of state in the process. This could be from run to shutdown or run to upset, or can even include a change from state 1 to state 2. This is because operating parameters change upon a change of state in the process and those changes cause the floods. This phenomenon can affect hundreds or even thousands of alarms. Therefore, upon process state changes, many alarms can sound in a short period of time. The first alarm or two indicate the initiating event, alerting the operator to the change. After this, many unnecessary and redundant alarms resulting from the same root cause are annunciated and displayed to the operator. If another situation develops, those alarms would be added to the existing flood of alarms without any differentiation between the two root causes for the operator. The operator is faced with evaluating these alarms for any process information they might provide, then acknowledging them. So many alarms can show up at once that this job can become very difficult. In fact, the observation has been made that so many alarms are going off that, by cause and effect, acknowledging alarms becomes the only response of the operator.

What is the problem?
The EEMUA, when speaking about the impact of alarm floods on catastrophic incidents, said “they were a major contributor, and the loss incidents frequently involved the operator being overloaded with alarm floods.”1

EEMUA Publication 191 provides several high-profile examples where poor alarm system performance (floods) contributed to financial loss, environmental damage, injuries or death. Based on this information, the following equality has been proposed to emphasise proper thinking and priority of alarm management projects for corporate managers, operations managers, and managers of industrial health, safety and environmental departments:

Floods = incidents = loss

Conversely, the control of alarm floods will result in fewer incidents, less loss and, as a result, lower risk. Industrial plants have reported lower insurance rates as a result of lower risk attributed to superior alarm management performance.

DUSTIN BEEBE, STEVE FERRER and DARWIN LOGEROT (July 2012)

Alarm floods and plant incidents Alarm floods and their contribution to industrial incidents can be controlled successfully through all process states

AN INTERLOCK BYPASS BITES AGAIN!
Some key points to be considered on any interlock bypass.
When participating in hazard reviews:

 Point out where interlock bypasses are used for getting the unit started or for any other purposes.
 In particular, discuss interlocks that can be manually bypassed.
 If bypass timers are used, ask, ’are the time-limits reasonable?’ They should be long enough to get started, without being so long that an incident could happen.
 Systems in bypass should be noted in the unit logbook and discussed during shift handover.

DNV Consequence analysis and QRA Product videos - YouTube

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I recently read an article on modern work trends that highlighted how the very tools designed to make our work more flexible and easy — emails, messaging apps, remote access etc — are now contributing to a growing sense of overwhelm. Microsoft’s latest research shows that the average worker can receive over 100 emails and over 100 Microsoft Teams messages every single day. That’s more than 200 interruptions daily, occurring while we are trying to deliver on our own actual work of the day.

This constant digital noise is creating what’s being called the “infinite workday” where boundaries between work and personal time are eroding, and people are logging back in early morning or at night just to keep up/catch up. It’s a contributor to why many of us are feeling stretched thin.

So, my message today is about being mindful of this and to take a moment to pause. Be kind to yourself. Respect boundaries of others. Check in on your colleagues—not just about work, but more generally about how they’re doing. These small acts of care and awareness can make a big difference.

We can’t control the pace of change we are all caught up in, but we can choose to lead and go about our day with empathy and care.

Credit to MR 8/07/2025

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Safety First, Laughs Second: Process Safety Done Right

Do you think that Process Safety should ever be fun?

Welcome to this month’s edition of Process Safety Dispatch, where we blend practical insight with just the right dose of caution – so you don’t have to lose sleep over potential hazards. Because while safety may not always steal the spotlight, preventing serious incidents before they happen is what keeps operations running smoothly.

The Holy Grail of Process Safety: Why It’s More Than Just a Fancy Name
Process safety is not your everyday, garden-variety “be careful with that slippery floor” type of safety. Oh no! We’re talking about the kind of safety that makes sure your plant does not accidentally convert into a fireworks display. Process safety focuses on preventing catastrophes like chemical releases, fires, and explosions. In short, it’s the superhero ensuring everything hums along as boringly as possible – and we wouldn’t have it any other way.

The Safety Pro’s Toolbelt: Gadgets Cooler Than James Bond’s
Who needs spy gadgets when you have hazard analysis tools that can literally save the day? Here are just a few gems from the process safety toolkit:

HAZOP (Hazard and Operability Study): The Sherlock Holmes of process safety, sniffing out potential risks before they become headline news.
LOPA (Layers of Protection Analysis): Think of it as safety’s version of wearing a belt and suspenders. Overachieving? Sure. Worth it? Absolutely!
Emergency Shut-Down Systems: The big red buttons that scream, “Save yourself!” but in a cool, calm, and collected way.
Laboratory Testing: Your behind-the-scenes detective, analyzing materials for combustibility, reactivity, and other hidden hazards before they become real-world problems.
Safety Gone Wild: Tales of “Never Again”
Let’s face it: some lessons in process safety come from the infamous “never again” moments of history. Take, for example:

The Great Molasses Flood of 1919 in Boston, when a tank burst, unleashing a sticky tidal wave that destroyed buildings and lives. Lesson learned: Always check your structural integrity – and maybe don’t store millions of gallons of molasses in one place.
The Texas City disaster of 1947, when a cargo ship carrying ammonium nitrate exploded, leading to one of the deadliest industrial accidents in U.S. history. Lesson learned: Flammable chemicals and heat? Not friends!
These incidents remind us of the ultimate goal: a world where “oh no!” is reserved for dropping your pen, not your chemical reactor.

Safety Culture: Where Everyone’s a Safety Rockstar
Let’s talk vibes – safety vibes, that is. In a thriving safety culture, everyone is on the same page. The CEO? Safety champion. The intern? Safety detective. The operator? Safety police. When everyone buys into the idea that process safety isn’t just an abstract rule but a way of life, magic happens. Or rather, disasters don’t happen, which is even better.

Quiz Time: Are You a Process Safety Whiz?
Are you ready to test your process safety prowess? Answer these quick questions:

What’s the first thing you do in a chemical emergency? (Hint: Don’t panic; James Bond never panics.)
True or False: Process safety is only for engineers. (Spoiler alert: FALSE!)
Why is HAZOP better than guessing? (Answer: Because guessing is for lotteries, not safety.)
Score 3/3, and you’re officially a process safety genius!

Final Words from the Safety Zone
So, dear reader, remember: process safety may not involve capes or supervillains, but it’s no less heroic. The next time you hear someone say, “Safety is boring,” just smile and know that boring is the unsung hero of a thriving workplace.

Stay safe, stay cautious, and most importantly, stay boringly brilliant! Until next time!

Source: Stonehouse Safety

Pressure Relief Valve Parts

Pressure relief valves (PRVs) are vital components in any pressurized system — from pipelines and boilers to tanks and compressors. Their primary role? Preventing overpressure that could lead to system damage or even catastrophic failure. Let’s break down the key parts that make a PRV function with such precision:

🔹 Cap & Stem
The cap covers the upper section, while the stem connects internal components, helping control the movement of the valve.

🔹 Compression Screw & Nut
These components adjust the spring's tension, which determines the pressure threshold at which the valve activates.

🔹 Bonnet
This protective casing supports the compression mechanism and houses the spring.

🔹 Spring
The heart of the valve. It resists pressure from below until the preset limit is exceeded — then it compresses, allowing pressure release.

🔹 Top & Bottom Spring Step
These hold the spring in place and align its force correctly during valve operation.

🔹 Handle, Stud, Stud Nut
These components help secure the valve assembly and allow manual adjustments if needed.

🔹 Guide & Point
They ensure smooth, precise vertical motion of the disc to allow or block flow.

🔹 Disc & Disc Holder
When pressure exceeds the set point, the disc lifts, releasing excess pressure. The holder ensures a secure and stable mount for the disc.

🔹 Nozzle
Directs the released fluid or gas safely away from the system.

🔹 Upstream & Downstream Fl**ge
These flanges connect the valve to the piping system, forming a sealed path for media flow.

🔧 Why It Matters:
A pressure relief valve is your system’s safety net. Each component is engineered to react instantly and accurately, keeping people, equipment, and operations safe.

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