Applicability of Codes and Standards to Piping 3

[dhoxworth]

How does one determine what code/standard applies to what? Our project has the requirement that all piping shall conform to ASME B31.3 because it is a chemical plant. Would this also apply to the vents which are PVC? I don't have the code so I don't know whether ASME B31.3 can apply to any and everything within the plant boundaries that has do with the process, regardless of use and material. Could someone please provide some direction and enlighten me here? Thanks.

 

[StressGuy]

I guess that depends on what you are talking about by vents. If these are vent connections on process lines, then B31.3 is most likely going to apply. If you're talking about vents for plumbing in the bathroom of the control room, those aren't going to be B31.3 lines, even though they are "in the plant"

For process piping, B31.3 has a whole section devoted to nonmetallic piping.

Since you don't have B31.3 available, I'm assuming that the piping you supply does not typically fall under it's umbrella.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[TBP]

There could be lots of piping codes that apply to your facility - plumbing, fuel utilization, fire protection/sprinkler, B31.1 might apply to the steam plant, B31.3 for the process areas, etc. There are also a lot of local spins on this stuff as well. Always best to check with the jurisdictional authority before spending a lot of money.

 

[davefitz]

The opening page of each ASME code defines the parts of the plant that it may specifically apply to or not apply to.

In addition , each state or locality may have a legal requirement for certain code applicability. For example, one might normally assume a B31. code would apply to fuel gas pipelines used within an individual plant bounday, but some states mandate that if the fuel gas is from an interstate pipeline then even the local plant fuel gas lines must meet federal regs, not B31..

 

[reichertc]

B31.3 defines pipe as "a pressure tight cylinder..."

I've always used this definition to waive any requirements for B31.3 (like hydrotesting and radiography) on piping open to atmosphere. I've been challenged by in several different jurisdictions by inspectors, specifically when I had a vent that could develop some pressure and potentially ran around 800°C, but when I showed them this definition, they backed right off.

I design based upon a good look at the specific system and set my own requirements based upon my comfort level for this piping.

Any of you B31.3 members out there feel free to blast me if you feel I am incorrect in my interpretation of the rules...

 

[moltenmetal]

That's been our interpretation of the codes too. Any piping which is relieved at less than 15 psig or is open to the atmosphere with no isolating valves between the pressure source and the atmosphere, are "exempt piping". The fabrication methods applied to "exempt piping" are at the owner's discretion.

 

[TBP]

I'm just getting involved with B31.3 (most of my work falls under B31.1), and I'm trying to understand more about it. What if the fluid is flammable, or classed as harmful to human tissue? Would that piping in that service not fall under B31.3, regardless of pressure or temperature?

 

[reichertc]

You really need to read the scope of the code. For example, I have required B31.3 compliance on systems that were very low pressure (7 psi), not open to atmosphere, and operating at a temperature of 800°F.

The key is to know what you legally/contractually need to do. In some jurisdictions I have been in, compliance with B31.3 is mandatory. However, one jurisdiction has excluded piping that is under 15 psi (regardless of service) from requiring compliance with B31.3. As such, assuming that the contract that I am working under does not require compliance for all piping, I am free to relax the requirements of B31.3 for a 7 psi, 800°F system. Other jurisdictions would not allow this.

I've always tried made it a practice to understand jurisdictional requirements, then contract requirements, and then my companies requirements before I even start trying to figure out what the code requirements are. I find it's much easier to understand how to apply the code this way.

Hope that helped...

 

[ytse]

The scope of the B31.3 code is not limited by the piping material of the pipe, just by it's service. (It DOES cover PVC pipe)
There are specific exclusions defined by the code. Paragraph 300.1.3 of B31.3 reads:
"This Code excludes the following:
( a ) piping systems designed for internal gage pressures at or above zero but less than 105 kPa (15 psi),provided the fluid handled is nonflammable, nontoxic, and not damaging to human tissue as defined in 300.2, and its design temperature is from -29°C (-20°F) through 186°C (366°F);
(b) power boilers in accordance with BPV Code2 Section I and boiler external piping which is required to conform to B31.1;
( c ) tubes, tube headers, crossovers, and manifolds of fired heaters, which are internal to the heater enclosure; and
(d) pressure vessels, heat exchangers, pumps, compressors, and other fluid handling or processing equipment, including internal piping and connections for external piping."

Based on the above definition, this all depends on whether the fluid in the vent is "flammable, toxic or damaging to human tissues".

Definitions from the code:-

damaging to human tissues: for the purposes of this
Code, this phrase describes a fluid service in which
exposure to the fluid, caused by leakage under expected
operating conditions, can harm skin, eyes, or exposed
mucous membranes so that irreversible damage may
result unless prompt restorative measures are taken.
(Restorative measures may include flushing with water,
administration of antidotes, or medication.)

flammable: for the purposes of this Code, describes
a fluid which under ambient or expected operating
conditions is a vapor or produces vapors that can be
ignited and continue to burn in air. The term thus may
apply, depending on service conditions, to fluids defined
for other purposes as flammable or combustible.

 

[TBP]

For what it's worth (and I strongly suspect it's worth something...)- from Becht's "Process Piping: The Complete Guide To ASME B31.3":

"The Code excludes low pressure piping systems from it's scope, if they meet all of the following conditions:

(1) the pressure is less than 105 kPa (15 psi);

(2) the pressure is not less than zero (i.e. no vacuum condition);

(3) the fluid is non-flammable, nontoxic and not damaging to human tissue;

(4) the temperature is not less than -29*C (-20*F); and

(5) the temperature is not greater than 186*C (366*F)."

If a fluid is characterized as "damaging", would that not include things like acids & caustics that you wouldn't really want on you, even if there was safety showers & eye wash stations in the immediate area, and if that water flush would remove the fluid? I worked at one plant where a maintenance worker got slightly splashed by sulphuric acid used for regenerating a weak acid dealkalizer set that was part of the boiler water pre-treatment system. He washed the acid off (and quickly, I might add), but it still left a visible minor burn across his cheek. Not particularly serious, in and of itself, but enough that I wouldn't like to experience that acid on my skin. I don't think the service would be classified as "Catagory M"., but I would like to think that that acid piping should have (and would have) fallen under B31.3, in some way. If not B31.3, then what?

 

[bvi]

TBP, in my opinion, damaging is damaging, so sulfuric acid would be damaging even if prompt action prevented permanent injury. The "promt restorative measures" is associated with the definition of Category M Fluid Service, not with the definition of damaging to human tissue.

reichetc, I would be careful regarding NOT applying B31.3 within its scope, because it may not be required by the jurisdiction. There is often more than one jurisdiction. In fact, most states do not require the use of ASME B31.3. But other regulations may do so directly (e.g. NFPA) or indirectly OSHA 1910.119 (follow recognized and generally accepted good engineering practice).

 

[TBP]

bvi - That's kind of how I was looking at it. If it's a fluid that you shouldn't breath/otherwise injest, have on your skin, in your eyes, or is deemed flammable (but not a fuel), then it very likely falls under B31.3, unless some other code covers it.

While things like catagory "M" service would fall very specifically under it, would it be correct to think of B31.3, as being in many respects, a sort of the "misc. file" for piping?

 

[bvi]

B31.3 a misc file? Not sure what you mean. It is for Process Piping, i.e. piping in process plants.

 

[TBP]

In most general industrial plants in this jurisdiction, the vast bulk of the piping will fall under plumbing codes, fuel utilization, B31.1 or B31.5. There's a lot of confusion regarding things like the acid piping mentioned in one of my previous posts. People (some people, anyway) in these plants recognize there's a hazard associated with the fluid, but are unsure as to just what code covers the piping for it. When considering an acid line in the boiler room of a general industrial manfacturing plant, what code would apply?

 

[dhoxworth]

what about vents that *may* contain very small amounts of hazardous vapors (e.g., HF)? would you say that B31.3 applies? and who makes that call? is that up to the engineer/owner or the state for example?

 

[bvi]

Selection of the applicable piping Code is the owner's responsibility. Of course, he may exercise that right using the advice of the designer.

Acid piping in a power plant is within the scope of ASME B31.1.

Regarding acid piping in a boiler room in an industrial facility, you would probably want to use B31.1, unless the industrial facility is a process plant.

 

[dhoxworth]

Acid piping in a power plant is within the scope of ASME B31.1.

Regarding acid piping in a boiler room in an industrial facility, you would probably want to use B31.1, unless the industrial facility is a process plant.

how about in a chemical facility? wouldn't that be ASME B31.3?

 

[bvi]

A chemical facility is generally considered to be a process plant, so yes, B31.3 would be applicable.

 

[TBP]

Just so I understand - One of the one of the determining factors regarding the requirement for piping in a particular service (acid, for instance) to comply with a piping code is "Is the fluid damaging to human tissue, regardless of pressure or temperature?" If the answer is "yes", then it stops being a question of whether or not the piping falls under a code requirement, but now becomes a question of which piping code applies?