Safe zone around purged vessel 2

[rocketscientist]

I work as a consultant for a pharmaceutical company that regularly allows their operators to access purged vessels. I was wondering if someone had come across an estimate for establishing a rough zone around an open manway. I am thinking of requiring SCBAs for this type of work but they do it so often it worries me.

Any thoughts?

 

[TiCl4]

You need to provide more details, the first and foremost of which is this: Are these vessels confined spaces? If so, then entrance into the vessel with any portion of the body is a confined space entry and has many conditions to clear before doing so. Is this a US or EU-based site?

Edit: Other details needed:
What does the vessel contain?
What is this "purge"?
What "entry" are the operators doing? Is this sticking a hand to grab a sample or is it full-body entry?
What governing agency is over the site? I.e. OSHA for US facilities.

 

[LittleInch]

Define " This type of work".

Sounds like sxternaal access to an open vessel manhole?

If there is no purge gas exiting then no more than 1D of the manhole as a semicircle?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pierreick]

Hi,
First and foremost, Do They issue an entry permit prior to enter the vessel, even for inspection from the manhole? Do they measure Oxygen content prior to inspect the vessel?
Yes, GMP requires a lot of inspection, not always done according to safety rules (vessels, reactors, hoppers, silos, etc.).
My experience with paracetamol and Aspirin facilities.
Talk to the HSE/Operations managers.
SCBA? I guess you never used one of them. This is not the type of equipment to use in routine.
Endoscope could be an option for inspection (?).
Good luck
Pierre

 

[crshears]

Post and ghost?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[rocketscientist]

I know it's hard to believe nobody in pharma heard of the Valero N2 purge accident covered by the CSB.

https://www.csb.gov/valero-delaware... overcome,the workers died attempting rescue.

Unfortunately, I am here to tell you it is true. In pharma it is not uncommon for operators to sample or add ingredients to a vessel or tank under purge. Of course, it helps that the purge pressures are low, perhaps 5 IWC above atmospheric pressure at best. Unfortunately, a lungful of N2 will probably cause unconsciousness. See "Use Nitrogen Safely," Paul Yanisko, Dennis Croll, Air Products, pg. 44-48, CEP, AIChE, March 2012.

They're not alone. I've seen workers at BP's refinery in Whiting dip level tape into open manways of hot propylene tankcars. It is the only way they can get a measurement they said. When I was at Anheuser-Busch in 80's operators stood on top of agitating fermenters, balancing over open manways to add sacks of nutrients.

So, the question I am asking is this: does anyone have a general practice (GP) for the safe radius around an open manway under purge?

My own approach would be to treat this as a confined space area until my client can establish that the air is breathable. Keep in mind the pharma is usually a batch process. Key operating parameters are established during the maiden run of a product. That's what I am advising: take measurements around the manway and establish if the conditions are safe. If not, then add SCBA, an attendee, personal %O2 monitors, and %O2 monitors. If marginal, then add %O2 monitors, personal %O2 monitors and an attendee. Attendee? Companies will have one operator by himself if they can.

So, what do you think?

 

[Latexman]

Addition systems can be engineered and built so the manways can be closed permanently, or until maintenance turnarounds occur. Decades ago, I saw the same thing where I worked. It's a management problem. Management has to decide whether exposing people is okay or not. There will be a lot of debate and hand wringing if they keep the manways open. But if they invest in the right equipment, the issue goes . . . poof! To me, it's a no brainer.

Good Luck,
Latexman

 

[LittleInch]

Only thing I can think of is to look at hazardous area classifications around vents etc. Zone 1.

Like this

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TiCl4]

Rocketscientist,

If your concern is the atmosphere around an open manway, that is a far cry from "entry" that you alluded to earlier. I would advise staying away from the term "confined space" when dealing with your situation, which, as I understand it now, involves adding chemicals through an open manway of an inerted vessel.

If your concern is only O2 depletion due to purging, then why not simply grab a four-gas meter and measure the O2% around the manway opening? If you have other chemicals of concern that are co-eluted, then an industrial hygiene study is normally done to ensure exposure limits are not reached. The main concern around the N2 is really the operator putting his face too close to the opening, passing out, and slumping over into the manway. I know of a company that has mandated guards be mounted on top of or inside manways which are accessible and need to be used by operators.

Latexman's suggesting of engineered systems for additions are good, but they take time to implement and are dependent on management's agreement to spend money for "non-value added" work. Other, faster means of providing a safer work environment should be explored in the meantime. Something as simple as a fan blowing across the manway opening to provide a fresh air stream could work, but may not be viable for your process. My first step would be to directly measure the O2% at different distances from the manway openings in order to gauge the actual risk involved.

Have you ever used a SCBA? Donning a SCBA to make a material add every batch is a non-starter. SCBAs are typically used for emergency response. Even supplied-air respirators are not much better, and requiring one to do the work is basically acknowledging that you know the operators are being asked to step into a O2-deficient atmosphere and you are only providing them with PPE to mitigate the risk. That's not an acceptable mitigation of risk, in my opinion. Find a better way to add the materials or engineer a solution to ensure the atmosphere outside the manway is breathable.

 

[rocketscientist]

TiCl4: Yea, I've used SCBA. It's difficult but doable.
Latexman: (We've met before online.) Pharma doesn't like to spend money on safety and they tend to be so ignorant of safety rules. They are too driven by quality.

When I did a stint at one of their plants to clean up HAZOP safety recommendations I found them woefully ignorant of the risks of flammable liquids and dust.

Everything is approved by quality: I told them that you can't worry about qc until you've safely made a product.

I think they'd go for the SCBA if deemed necessary. Their production, like most batch operations, is very hands-on. Their control systems are tied up in new product formulations without extra for in-depth safety monitoring. (I've done project work at 2 different pharma companies.)

I did leave an out for them that they will like: certification. Pharma likes to validate their process procedures so their use of a manway can fold neatly into this step. Run the product prove there isn't a problem at the manway then put safeguards in place. I've learned to use the tools clients let me have and pharma does like its validation process.

LittleInch: I like the electrical area classification approach. I should have remembered that. I am an EAC expert. I will include the barrier limits based on API-500 or NFPA-497, if you wish. Thank you.

 

[TiCl4]

Rocketscientist,

And will the pharma company be prepared to re-fill the SCBA every use? OSHA requirements for SCBA require they be 90%+ full before each use. For a standard 45 min to 60 min tank, that pretty much means they will have to be re-filled after every use (6 mins of use before refill). NFPA-certified fill stations are not cheap, either.

Rather than mandating SCBAs, SARs, or other measures because of a "feeling" of unsafe acts, it would be prudent to go collect the data to prove there exists a zone of O2 depletion around the open manway. Otherwise, your words and consulting advice has very little worth.

 

[pierreick]

rocketscientist,
You did not read my reply, not a big deal. Latexman gave you the answer, you need to talk to HSE and OPS managers.
SCBA is not an option, and you know it.
A link about powder transfer:

https://www.dedietrich.com/en/solutions-and-products/powder-handling/powder-pump

Be prepared to spend $$$, one reason the Pharma business delocalizes their operation.
You and FDA guys and other agencies are "good" at paperwork (NC, corrective actions, warning letter, etc) but you have no idea about operation/people/budget/action plan implementation.
Pharmaceutical and Chemical industries are two different worlds.
My view only.
Pierre

 

[Latexman]

Latexman: (We've met before online.)

sts098?

Good Luck,
Latexman

 

[georgeverghese]

One solution is to make it compulsory to free ventilate the vessel prior to vessel access. This is usually done under work permit procedure, where procedures are carried out under supervision. For larger vessels, may be safer to enable continuous cross forced ventilation for as long as manways are open. Obviously, vessel should be POSITIVELY isolated prior to purging. Work permit procedures and methods must be built into Operating culture for this to work.

 

[shvet]

@rocketscientist
Note that one shall assure that velocity in an open loading nozzle is above some min limit to avoid air backflow. Maintaining positive pressure inside of vessel is not enough to prevent air ingress. Having experience in calculating such for process vents I should warn you that the amount of an inert gas escaping is huge. This is the reason why most such design involved some devices on mounted on top of a loading nozzle to segregate vessel from ambient air.

 

[LittleInch]

So if I understand this correctly, operators go to a tank under small purge pressure (5 "wc), open a manhole or other opening and either get a sample or add some? powder or liquid. Then close the manhole again?

Can you not add airlock type nozzles?

Or something that pushed the material in using the purge gas?

Openings will destroy your purge in a short time and consume large volumes of purge gas. Surely that is of interest to the company from a quality and cost point of view?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rocketscientist]

shvet: Yes, by law in vent systems, a certified measured velocity of 50 fpm (min.) is acceptable at the "shash" of the vent (Lab vents have a gap below the window.). This rule applies to all hoods and vent intakes. Generally, engineers design for about 100 fpm to be safe.

Oh, and that is a good idea.

LittleInch: nope, I've seen it done while the vessel is purged: common practice. (Just like I've seen operators pulling the nozzle stems from an HCL acid regeneration reactor without air apparatus or even a respirator. I've done it myself but I wear a respirator.)

Airlocks won't work because of cost, another good idea though.

georgeverghes: not practical. Remember we're making product here, not filling out OSHA forms--- crossing T's and dotting I's. Besides, this sort of behavior is built-in. Nobody has died, as far as I know. (I remember the story of an electrician from the 1930's who testing if circuits were live with wetted fingers. When I worked at Anheuser-Busch, I regularly tore down motor boxes. These are things I cannot do because some idiot got hurt --- being an idiot.)

TiCl4: the pharma company is pretty fastidious about their procedures so I think they could be trusted to keep the air tanks filled for a 5-minute excursion.

pierreick: trouble is that relocating operations brings its own problems. That explains why manufacturing is gradually picking up in the states. Companies can't trust on-time, quality supplies from around the world ( China, India), especially after a pandemic.

The reason why I asked this question was because I am re-writing the safety standards for a pharma company. I AM SAFETY.

As for regulation, pierreick, I don't find it burdensome. Regulation prevents our managers from killing operators --- and engineers wholesale. Besides, once you do the forms it's much easier. I remember doing my first RCRA report in 1988: sure it was a challenge the first time but it was much easier the second. The same for emission reports. It is better to have people in an area happy to have the jobs, knowing that the chemical manufacturer, including pharma, is following the rules.

What has me concerned is Chuck Koch winning his war against regulation in fall 2024. Those regulations protect us all; they keep us responsible. The next time your boss wants you to sign the paperwork when he dumps polluted wastewater to an unsuspecting city water plant remember that Chuck Koch put you on the hook.

Companies caught in the act will tell you that the lawyer hired represents you: that is a lie. That lawyer is there to serve you up to the court.

 

[TiCl4]

A last point of mine may have been missed. Have you or anyone else actually measured O2 concentration near the manway? Before you call it an issue and put in countermeasures, you need to actually prove it is an issue, and to what degree.

 

[EdStainless]

I have seen this in pharma and in PCP (personal care products, soap, shampoo, etc).
The most common system (other than nothing) that I have seen was a plastic shoot that fit to the flange.
It gave the operator a nice clean way to make an addition, and it had a vent that directed purge air and/or fumes in the other direction.
If the vessel was under purge the operator making the add always wore an oxygen monitor.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Latexman]

Back in my old phenolic resin days, after the operator opened the vent and cracked the man way open < 1 inch they would put a slight vacuum drag (negative pressure) on the still before opening the man way wide open. Man ways had cross bars so no one could fall in.

That was 40 years ago.

Addition systems took their place.

Good Luck,
Latexman