How to define mainline block valves by B31.4 1

[LuisF83]

Hi:

I have some troubles defining mainline block valves, ASME B31.4 refers to "major river", but how to define it, how depth?, width? flow rate?. The pipeline has 27 km, and cross at least 4 rivers and 15 marshes and swamps.

How many mainline block valves I have to put on it?

Best Regards,

Luis Felipe

 

[barlow12358]

hello

The ASME B31.4 does not indicate anything about how to define a major river.

In my experience should consider environmental factors, response times to an incident.

Rios over 15 meters and its main tributaries distances greater than 1000 meters should have block valves and systems for immediate response.

regards

 

[BigInch]

A 27 km pipeline might only have inlet and outlet "mainline" block valves, 2 in total, provided that the terrain it crosses is not too sensitive and perhaps the pipeline is of a relatively small diameter. It is a question of how much product volume can leak from the pipeline and how much and what kind of damage that leaked volume of product might do. If it was a crude line, or a propane product line, the risk would be quite different, so each case needs to be evaluated on its specific criteria.

A small diameter line might not require any intermediate valve. Remember, every valve added increases the risk of a leak, so there is an optimum number of valves that any given pipeline should have. Block valves will rarely be less than 20 miles apart, unless increasing the risk of a leak by installing another valve can be balanced by reducing that risk by leaking only a smaller volume of product. d

My opinion on this is that, if this area is a sensitive area and potential for injury is high or endangered species are involved, humans could be hurt, tourism would suffer, whatever etc. please consider that this pipeline is already pretty short as pipelines go and any leak will be relatively small in terms of how big pipeline leaks tend to get sometimes, so I would say, go around this area. Don't try to decrease the risk on this one by adding more valves into an already short pipeline. You may only be increasing the chance of a leak.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[elylrc]

I would not be concerned about mainline block valves leaking. First they are welded into the line and many, like Cameron and Borsig have all welded bodies. The likelyhood of pipeline dammeage, i.e. is there any traffic on the river, and the environmental impact of a leak should be your primary concern.

 

[DLite30]

See 49 CFR 195.260.e Valves: Location

(e) On each side of a water crossing
that is more than 100 feet (30 meters)
wide from high-water mark to highwater
mark unless the Administrator
finds in a particular case that valves
are not justified.

 

[BigInch]

"the Administrator finds in a particular case that valves are not justified."

Precisely my point. This could easily be one of those cases, if the diameter is small, for example, if pressures are low could be another, if other measures are taken, such as increased inspection frequency, such as a dynamic leak detection system is installed, if extra wall thickness is used, ... etc., etc. etc.

A weld is a weld and two, or four more of them is two, or four more of them. The fact that welded, or flanged, valves, any additional weld in fact, can increase the likelyhood of a leak has been well known for many years and the probability of such is used to optimize both the number of valves required and their placement, when such is not specifically mandated by precise regulation.

Precise block valve placement on a pipeline is recommended only after a carefully done valve location study is made considering all risk factors and possible leakage volumes against, length, volume, pressure and profile factors, including those from having more valves than you need.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus