03-14ST-Sampling LNG and LPG

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SAFE TALKSAMPLING NATURAL AND PETROLEUM GASES

OIL, GAS AND CHEMICALS SERVICES MARCH 2014

Introduction

Extreme care, good judgment and skill are required when sampling liquefied petroleum and natural gases.Because of the hazards involved they should be sampled by, or under the supervision of persons with thenecessary experience and using only approved equipment and procedures.

You must not take these types of sample if you have not received the appropriate training .

Primary Hazards

The primary hazards and concerns associated with this type of sampling are:

To prevent the material coming into contact with or being inhaled by the sampler or anyone else who maybe in the immediate vicinity. All of these materials are toxic and rapidly change into a vapor. Some arepoisonous, corrosive or both.

To avoid a rapid release of pressure; or, releasing the pressure onto an unsecured object. This could turnyour sampling device into a missile.

To avoid thermal burns due to the extreme cold. Some products are kept at extremely low temperatures tominimize pressure.

To prevent unacceptable pressures building up inside the sample container, once taken. In this regard, theymust be handled, transported and stored correctly.

Personal Protective Equipment

Before sampling any material review the Safety Data Sheet for that product to determine what personal

protective equipment is needed. Pay particular attention to the type of respiratory protection required. Alwayswhere a face shield in addition to goggles when sampling corrosive liquids,.

Sample Container Types

There are a number of different types of containers used for sampling gases. The following are five of the morecommon types; however, other types of containers may be permissible; however, all must meet national andlocal requirements and it is the responsibility of the supervisor in charge of the operation to ensure that allcontainers used are approved for the type of material that will be sampled.

Sampling a balloon or glass mouse – limited to vapor sampling only.

General purpose 1 liter cylinder, which has a maximum working pressure of 12,500 kPa (1800 psi). Thistype of cylinder is typically used for butane, butylene, propane, propylene and butadiene, usually referred to

as propanes, butanes and pentanes. They are also used for anhydrous ammonia.

High-pressure 0.5 liter sample cylinders. This type of cylinder has a maximum working pressure of 35,000kPa (5000 psi) and is used mostly for sampling ethylene vapor.

Floating piston cylinder or constant pressure cylinder . This type of device collects the fluid samples bydisplacing a pressurizing fluid (usually inert gas) and therefore maintaining a constant sampling pressure.The piston forms a barrier between the sample and the inert gas.

Sample cylinders must be corrosion resistant to the material being sampled.





Filling Instruction – Vapor Samples

This type of sampling is usually performed at the uppermost top sample point of the tank and must beperformed under low pressure conditions. For this typeof sampling a balloon (bag or bladder) or glass mouse isrequired. Before use, the sampling container must bepurged with nitrogen to avoid contamination fromresidues of previous samples. After connecting to thesampling point the container is purged by filling it withvapor from the tank and then emptying it. This is typicallyrepeated twice or until the container is consideredpurged. After purging the container is then filled with the sample that will be analyzed in the laboratory. As only

a limited range of tests can be performed on this type ofsample, only small sample volumes are required.

Retain of vapor samples is not possible. Any amount ofsample remaining after completion of the analysis is notconsidered suitable for additional testing at a later date.When using sample balloons in which the inlet connectionis also the outlet connection, special attention is requiredduring purging as the bag must be disconnected from thesampling point and care must be exercised to ensure thatoxygen or moisture does not enter the sample bag.

Filling Instruction - General Purpose Cylinders

The general-purpose cylinders are fitted with two valves, a rupture disk and a dip tube. The dip-tube is alwaysplaced at the same end of the cylinder as the rupture disk. The cylinder should be etched with a serial number,the location of the dip-tube and if Teflon coated this should also be indicated on the outside of the unit.

In addition to the markings on the body of the cylinder, there is a metal tag attached close to the rupture diskhousing. Rupture disks must be replaced every year and the date on this tag indicates when the rupture diskshould be replaced. Do not use a cylinder whose rupture disk is out of date.

1. Examine the sample cylinder to ensure that it is in good working order and the rupture disk is current. Also,determine which end of the cylinder the dip-tube is on.

2. Weight the empty cylinder.3. Ground the cylinder to the sampling point, using the grounding cable provided.

4. Purge the sample transfer line by displacing at least 150% of the line's volume from the tank to the samplingpoint.

5. Attach the sample cylinder to the sampling point with the dip-tube closest to the sampling point connection.See Figure 1.

6. Slowly open the sampling point valve (not shown in figure 4.6.3-1) to allow material to flow to valve "A" ofthe cylinder.

7. Purge the cylinder. Slowly open valve "A" then partially fill the cylinder by slowly opening valve "B". Closevalve "A" and allow the material inside the cylinder to vent through valve "B", preferably via a bleed-off line.

Glass Mouse





8. It is normal to purge the cylinder three times. After final purging closeall cylinder valves and commence taking your sample.

9. Slowly open valve "A", which will allow material to flow into thecylinder. You will notice a cooling or freezing effect on the cylinderclosest to valve "A".

10. Slowly open valve "B" to allow for displacement of vapor. Close valve"B" when you observe liquid coming from it.Note: Do not open valve "B" fully or too quickly as this may cause the

liquid material in the sample to evaporate and you will only havevapor in your cylinder.

11. After you have closed valve "B", quickly close valve "A". Depressurizethe sample fill line and disconnect the cylinder from sample collectionconnector.

Caution: Your cylinder is now liquid full and it is critically importantto create a 20% to 25% vapor space inside the cylinderimmediately. Do not perform any other tasks prior to this, asthe pressure inside a liquid-full

cylinder will increase 600kPa for every 1°C (50 psi for every 1°F) rise in temperature.

12. While the cylinder is still grounded, invert it so that the dip-tube ispointing straight up. The dip-tube indicator arrow () will also bepointing upwards.

13. Slowly open valve "A" until you observe liquid escaping from it.14. Allow liquid material to escape from the cylinder through valve "A" until

the liquid material changes to vapor.

15. As soon as you observe the escaping liquid change to a vapor, quicklyclose valve "A" and weigh the sample.16. Using the safe-fill table provided, ensure that the weight of your sample

does not exceed the weight of 800-ml of the material you are samplingplus the weight of your empty cylinder. If it does, repeat steps 12 - 16until it does not.

17. The receiving laboratory is to verify the cylinder weight upon arrival atthe laboratory.

18. After you have created the required vapor space inside the cylinder,place plugs into both valve openings, label the sample and prepare itfor transportation.

Note: If the material sampled is anhydrous ammonia or butadiene, immediately place the sample in ice or put itin an explosion-proof refrigerator to prevent reaction from the material sampled.

Filling Instruction - High Pressure Vapor Cylinders

These cylinders are longer, thinner and heavier than the general-purpose cylinders. They have a much thickercylinder wall with a rated maximum working pressure of 35,000 kPa (5000 psi). and an internal capacity of 500ml. These cylinders have a valve on each end and a pressure gauge; however they do not have a pressurerelease device or a dip-tube.

1. Examine the sample cylinder to be sure it is in good working order, equipped with a high pressure gauge (0 – 35,000 kPa / 0-5000 psi).





2. Ground the cylinder to the sample point using the grounding cable provided.3. Attach the sample cylinder valve "A" to the sample point.

4. Open the sampling valve to allow material to reach valve "A" ofthe sample cylinder.5. Slowly open valve "A" of the sample cylinder to allow the sampleto flow into the cylinder. You may notice a cooling or freezing of thelower part of the cylinder.

6. Slowly open the valve "B" to allow displacement of the vapor inthe cylinder until ethylene vapor is observed flowing from the top ofthe cylinder.

Note: Do not open this valve too fast. This will allow the sampleto flow straight through the cylinder and you will not have any samplein the sample cylinder to deliver to the lab. Allow product to flow

through the cylinder for about one (1) minute allowing time to displaceany air or nitrogen that may have been in the cylinder previously.7. After you have filled the sample cylinder completely, close thevalves "A" and "B".8. At this point you will have some liquid in the sample cylinder.

Note: With ethylene, the object is to obtain a vapor sample,therefore you must ensure that all liquid material is vented from thecylinder , immediately. Do not perform any other tasks until you havedone this. A properly caught sample should contain between 700 –900 psi of high-pressure ethylene.9. While the cylinder is still grounded, depressurize the fill line anddisconnect the cylinder from the sample point. You will notice thepressure increasing on the pressure gauge. This is a result of the

liquid contained in the cylinder expanding to the vapor-state within thecylinder. The pressure will continue to increase to an unsafe levelunless vented. Open the sample valve slowly, vent the sample untilthe pressure reading drops is 800 psi. Shut-off the valve and observethe pressure gauge; it will probably begin to increase a second time.Keep venting the sample until the pressure stabilizes to 800 psi andholds that pressure for at least 10 minutes. It is recommended that a

bucket with warm water is taken to the sample point and the sample cylinder immersed in it to insure thatthe liquid sample has fully expanded.

10. Ensure that both cylinder valves are tightly and place plugs in the openings at the ends of the valve.11. Label the sample and prepare it for transportation.

Filling Instruction - Floating Piston / Constant Pressure Cylinders.

This type of sampler collects the fluid samples by displacing a pressurizing fluid (usually inert gas) and thereforemaintaining the sampling pressure. The piston forms a barrier between the sample and the inert gas.

1. It is important to follow the manufacturer'sinstructions as these units vary in design andconstruction.

2. A transfer line is still needed although some modelsare supplied with their own exhaust valve.

3. You must sti ll prov ide a 20% vapor space[maximum fill].





The above referenced procedure is to be used as a guide and to be considered typical rather than obligatory. Always refer to the manufacturer's instructions for both pre-loading and filling.

Safe-Fill Table

* Ethane samples should be taken using the same cylinders as areused for ethylene, with a maximum liquid volume of 20%.

The final weight of your cylinder should not exceed the Safe-FillTable Weight plus the weight of your cylinder when empty

Sample Transfer Line

The sample transfer line is an integral part of the operation. The mostsatisfactory transfer line is one equipped with two valves up stream ofthe sample container. If a vent valve is not available, a bleed-off hoseattached to the outlet valve will achieve suitable results. Both the ventline and the bleed off line should discharge as far away as possiblefrom where the samples are being taken.

Sampling Points

Both vessel and shore tanks are fitted with sampling points, whichcan differ depending on the size of the tank. Typically, tanks are fitted

with three sampling points that are equivalent to upper, middle and lower spot sample points as defined in themanual sampling standards.

An additional sampling point is also usually installed after the outlet of the cargo pump. The importance of thissampling point is that it allows samples to be taken while the product is being recirculated and for refrigeratedproducts this is the only way that samples can be taken due to the absence of pressure in the tank.

Transportation

Each sample must be labeled directly after sampling, followingthe labeling requirements of your country. All samples must betransported in a box of an approved type and in such a waythat the samples are secure inside the box and provideadequate protection to the cylinder's valves.

Additional requirements, specific to the transportation ofpressurized samples are:

Pressurized cylinders must not be placed in the cab ofa vehicle.

Pressurized cylinders must not be used if the rupture disk is older than 1 year.

You must have received training as specified in your national regulations within the previous three years.

You must have a SDS, for the material you are transporting, attached to your shipping papers.

All cylinders must be tested and approved; however, the regulations are mostly national in nature and this can

Grams Ounces

630 22.0

71 2.5

405 14.5

415 14.7

Propylene Oxide 660 23

465 16.5

450 15.5

480 17.0

Butylene 480 17

480 17.0

480 17.0

480 17.0

525 18.5

500 17.5

495 17.4

550 19.5

Material sampled

Acetaldehyde

Ethane*

N-Butane

Propane

Propylene

1-Butene

1,2 Butadiene

1,3 Butadiene

Iso-Butene

Iso-Butane

Trans 2-Butene

Cis 2-Butene

Ammonia Anhydrous

Isoprene





be problematic if a customer requests to dispatch samples to other countries. It should be noted that UScylinders are not approved for use in Europe, but European cylinders can be used in the US. Also, when pricingthis service we need to factor in the cost of retuning the empty cylinder as they are too expensive to discard.

Storage

Vapor samples cannot be stored. Liquid Gas samples can be stored; with the exception of ethylene whichcannot be stored as the time between sampling and analysis is a maximum 5 hours. Butadiene must be storedin an explosion-proof refrigerator between -5°C and 0°C. Additionally, butadiene samples must placed in arefrigerated box for transport immediately after sampling.

The retain period for gas samples is usually negotiated with the client, in line with their needs. For domesticoperations this is typically in the range of 2 days to 2 weeks. For vessel loadings, this will depend upon the

voyage criteria as there may be several loading and discharge ports, and the sampling period should ensurethat the samples are available until all cargo is discharged from the vessel.

Due to the high investment cost associated with having enough gas sample cylinders available, retain storagefees are normally charged by the week. Also, offices that do not have regular gas inspection work may not havecylinders available for retain samples.

Cleaning and Maintenance

The cleaning procedure outlined is applicable to flammable liquefied gases such as propanes, butanes,pentanes, etc. All flammable gas cylinders must be flared in a hood.

Examine the sample cylinder to be sure it is in good working order and contains a rupture disc. Determine

which side the “dip tube” is on and make sure the rupture disc has been replaced within one year. Tag and remove the cylinder from service if any negative conditions exist. Document the condition of the

cylinder and schedule it for repair or replacement, if required.

Attach the cylinder to the cleaning manifold. Use a grounding cable or equivalent if T-tape is being used onthe threads of the manifold.

Place the flare attachment fitting to the top of the sample cylinder. Attach the flare tubing to the fitting of thesample cylinders.

Open the cylinder valve to allow the sample to reach the bottom valve of the flare. Open the valve andignite the sample flare. Allow all hydrocarbons to completely burn through the flare system.

When the contents of the cylinder have been completely vented through the flare, open the bottom valve ofthe sample cylinder (dip tube end down) to allow nitrogen to flow into the cylinder and through the flare for atleast 5 minutes.

Slowly close the cylinder valve farthest away from the dip tube, so as to shut off the flow of the nitrogen tothe flare. Remove the hose and flare attachment fitting from the cylinder. Pressurize the cylinder to 1400 –2000 kPa (200 – 300 psi) with nitrogen, then close the bottom cylinder valve. Shut-off nitrogen to thecleaning manifold and remove the pressurized cylinder and check for leaks.

Check for leaks by submerging the cylinder valves in water and visually check for bubbles from escapingnitrogen. If you observe nitrogen bubbling from a fitting connection, valve, or rupture disc, consider this afailure of the leak-check. Depressurize the cylinder, in a hood, remove it from service and tag it for repair.

If sample cylinder passes the leak check, dry and plug the connections and place it back into service.

In cases where the cylinder is to be used to sample a product with a nitrogen specification, helium should beused on the final purge instead of nitrogen.





Minutes of Safe Talk Meeting

Branch:_______________________________ Divis ion: ______________________________

Person Conducting Meeting:__________________________________________________

Attendees:

Addi tional Items Discussed:

Problem Areas or Concerns:

Comments:

The original is to be maintained at the Branch forreference and audit purposes. Data from this fo rm is

required as part of your monthly Global QHS&E reporting

03-14ST-Sampling LNG and LPG

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