Blowing-Down Acetylene Cylinders

Purpose and Scope 2 Global Guidelines 2 Blowing Down Gas in Acetylene Cylinders 2

Purpose and Scope

Purpose This chapter contains procedures for blowing down acetylene cylinders.

Scope This chapter applies to Linde Bangladesh Ltd.

The target audience is all staff responsible for blowing down acetylene cylinders.

Global Guidelines

Guidelines Before using the procedures in this chapter, you must be familiar with the global guidelines in:

ACE-06-11 : About Blowing Down Acetylene Cylinders

Blowing Down Gas in Acetylene Cylinders

BOC and private

cylinders

Strangercylinders

Linde and Private cylinders must be blown down on the blow back

rack that returns the gas to the low-pressure pipe-work on the suction side of the compressors.

Stranger cylinders must be blown down on the blow back rack.

They must only be blown down using a manifold that vents gas to atmosphere at high level.

Step Action

1 Ensure the cylinder is correctly labelled/tagged for blow down.

2 Weigh the cylinder and record the weight on the label/tag/Logsheet.

3 Ensure that the generators and compressors are running at all times when blowing back to avoid over

pressurising the plant.

4 Place the cylinder alongside connection point on the blow down rack, with the cylinder valve handle facing out

from the rack.

5 Connect hose to the cylinder.

6 Open the cylinder-valve one return.

7 Open the rack blow down valve one return to blow gas back.

8 Check the following for leaks:

• All cylinders

• All blow down rack connections

Step Action

9 Leave the cylinders on the rack until pressure is 1.5 bars. Then leave the

cylinders for 2 hours further to warm the ambient temperature.

Do not add any more cylinders to the rack during this blow down period. Blowing down too quickly may chill the cylinders excessively. This results in the cylinder re-pressurising when they warm up to ambient temperature.

Low pressure generators: The flashback arrester by-pass valve can be opened

when the rack pressure falls below 1.5 bar.

10 Check the rack pressure gauge still shows zero pressure and all cylinders show

no sign of frosting.

11 Close the cylinder valves and blow down valve.

12 Disconnect cylinder/s and remove from rack.

13 Weigh the cylinders again and record the actual gas blown back so it can be

deducted from the gas produced in the carbide yield calculations.

Blowdown identification

No loss of weight

Excessive weight loss

All cylinders that have been blown down must be identified as being empty and safe to devalve by a suitable tag. However, where devalving is done immediately after blow down by the same operator, there is no need for the cylinder to be tagged providing the cylinders are temporarily stored in a designated area that clearly identifies that the cylinders are blown down.

If the cylinder has not shown a loss of weight, it must be regarded as possible blocked or broken valve. These cylinders must be tagged as “Blocked Valve” and sent to the examination area for further inspection.

To comply with the global guidelines (ACE-06-11 : see About Blowing Down Acetylene Cylinders) removing acetylene as from a cylinder with a blocked or broken valve must be done strictly according to the risk assessed process described in ACE-06-13 : Blowing Down Cylinders with Broken Valves.

If the cylinders has lost an excessive amount of weight (more than 1% of the tare weight) it should be set aside for examination by the supervisor.

Prepared by Reviewed by Approved by

………………………………... ....….………………….. ..…………………………..Kafi Mahmood Nahin Bashir Hossain Khalilur Rahmana Plant Engineer Maintenance Manager Area Manager

Ref :ACE-06-12-PH