Lifting TSVs in Loading Lines

[sshep]

Friends,

I know some of you are experts on this subject. We have a loading bay fed from distant pumps approx 1km away, with the pipelines protected by thermal relief valves to grade. Several times a year we have a TSV lift and not reseat causing spillage. Some of these events could be thermal expansion, but many are likely to be hydraulic hammer. The hammer would be caused by rapidly closing valves, either manual 1/4 turn valves or automatic quick closing valves.

Can a bladder type accumulator help mitigate hydraulic hammer effects? We are considering installing some of these accumulators to protect against thermal expansion of liquid in these and other pipelines, but maybe we can solve both problems at once.

Any recommendations on technical resources, equipment recommendations, best practices, etc to solve the problem is appreciated.

best wishes,
sshep

 

[ash9144]

An accumulator would minimize the effect you get at the specific points.
However it doesn't eliminate the hammering effect. You would still hammer your pumps would could cause you major head aches down the line. You might want to look into changing procedures, installing a recycle line for the pump, or just different type valves. I've also seen hammering cause pipe to separate from its flanges in a few cases.

 

[dcasto]

ash9144 is correct. The look at getting rid of the thermal relief valves by have a small check valve vent the material back to the suction of the pump or to a thermal sink point like a buried line.

 

[ApC2Kp]

sshep,
A pipeline of 1 Km length could definitely result in concerns for hammer. You don't mention pipe diameter, flow rates, or pressures - these would figure into hammer analysis. It would better to avoid hammer by operational design and procedures, as mentioned by ash9144, particularly the valve closing rates for actuators.
Sometimes, the controls may dictate requirement for fast shutoff of valves. A flow diverter instead of shutoff could be another approach with return flow to vessel.
If you need to consider accumulators, there are Blacoh or Flexicraft units that usually are applied as pulsation dampeners. The design pressures could be a limit, compared to the peak pressures of hammer.
A piping expansion chamber (stand pipe ?)might be needed for higher service pressures - something like an inverted drip pocket or mud boot, except it would have gas vapor pocket for expansion volume.

 

[MortenA]

In short: You may actually overpressure your pipeline several times a year. I think you take that very calmly

Another suggestion would be a anti surge valve at the valve (more than one hmm disable them?)

Best regards

Morten