APPENDIX 7: RECEPTION AND STORAGE

1. Purpose

The checklist should be used for a self-audit by the customer. It can as well be used as a guideline for the safety service of the supplying company. See Section 6.1.4.

2. Scope

This scheme shall apply to the reception of styrene by road or rail at all customers.

The principal objective is to ensure that the transfer of styrene from the delivering vehicle to the storage tank can be carried out safely. However, because the storage system and procedures may affect the safety of the unloading operation, these also need to be considered.

The scheme should also be used to:

a) Assess and record any changes in policy, attitudes or equipment since the previous check.
b) Obtain customer's comments on the transport operation and equipment being used.

The attached guidance notes provide an explanation of the check-list, and recommended minimum standards in certain cases.

3. Styrene Unloading / Storage Checklist

CUSTOMER:
DATE:
ADDRESS:
PERSONS INTERVIEWED:
VISITED BY:

3.1. The Unloading Area

1. Ease of access
2. Housekeeping
3. Separation of other activities
4. Ability to mobilise road tanker/rail car in case of emergency
5. Facilities to isolate area and restrict access
6. Fire fighting systems
7. Electrical classification
8. Minimum safety distances should be 15 m. between the off-loading point and storage, ignition sources etc.
9. Hoses/unloading arms
10. Earthing point
11. Protection against pipe damage
12. Other vehicles and trucks movements
13. Are hoses on truck clean and qualified for styrene?
14. Spillage controls systems
15. Hazard labelling of unloading points
16. Visual and audible alarm

3.2. The Unloading Personnel and Equipment

1. The presence of customer's operator/ driver self-unloading
2. Operator's experience, training and seniority
3. Deputy availability
4. Hose testing and renewal policy
5. Fixed unloading arm testing and maintenance
6. Availability of suitable safety equipment
7. Communication system
8. Use of dedicated loading / unloading lines

3. 3 The Unloading Operations

1. Written procedures
2. Hose purging and leak testing
3. Sampling procedure
4. Atmospheric/personal monitoring
5. Method of unloading (for example nitrogen pressure, pump - pump preferred)
6. Safeguards for pump
7. Emergency response
8. Emergency stop

3.4 The Storage Tank

Site

1. Bunded?
2. Shared? If shared, with what ?
3. Separation distances
4. Emergency disposal facilities

Construction

1. Construction materials
2. Insulated
3. Uninsulated
4. Refrigerated
5. Fire fighting systems
6. Earthed
7. Agitation
8. Blanketing
9. Fire protection
10. Internal coating tanks
11. Design pressure
12. Maximum allowed working pressure
13. Date and type of last test, inspection
14. Dip inlet pipe

Relief Valves

1. Separate
2. Combined with interlock
3. Size
4. Venting to: (Stack, Scrubber, Other)
5. Flame arrestors
6. Nitrogen purge vents

Instrumentation

1. Nitrogen blanketing pressure
2. Control points:

• Temperature
• Pressure
• Level

3. Are control and alarms independent?

Monitoring of Storage

1. Temperature
2. Pressure
3. Level
4. Piping
5. Pumps
6. Valves
7. Gaskets
8. Hoses

4. Storage Tank to Process

Precautions to prevent process streams contaminating storage vessels.

4.1 Procedures

There should be written procedures available for the following:

• Unloading styrene
• Testing, inspection and maintenance of equipment
• Emergency procedures

5. Customers Comments

Guidance notes for styrene unloading/storage checklist:

The reference numbers shown below relate to items shown on the styrene unloading / storage checklist.

5.1. The Unloading Area

1.1. There should be sufficient space for easy access of vehicles

1.2. Unless it is connected to the unloading facilities, it should be possible for the vehicle to be removed from the unloading area in the case of an emergency

1.3. Barriers, warning notices are required. Special consideration may need to be given to prevent shunting close to the unloading area

1.4. A foam or powder-based system is recommended.

1.5. This should be in accordance with national regulations.

1.6. Unloading arms are prefered to hoses

1.7. The earthing point should be checked on a regular basis.

5.2. The Unloading Personnel and Equipment

2.1. The customer's operator must be present during off-loading and maintain control of the styrene unloading area. If the driver unloads the cargo, he should be trained and certified by the receiving party, to operate the installation according the unloading procedures.

2.2. There should be at least two trained deputies to provide cover for illness and holidays

2.3. Consider general protective equipment. Goggles should be worn. A safety shower and eye fountain should be sited adjacent to the unloading area.

5.3. The Storage Tank

The sizing of styrene storage tanks should be the smallest compatible with shipping and receiving requirements.

Storage times in excess of 3 to 6 months should be avoided to minimize degradation of styrene quality.

5.4. Construction

Construction materials

Carbon steel and stainless steel are suitable for handling styrene. No copper nor material containing copper as an alloy element should contact liquid. (Copper can discolour the styrene and has been known to cause polymerisation in some applications).

Insulation and Refrigeration

Styrene storage tanks do not normally require insulation or refrigeration unless extremely high temperatures are likely to be encountered.

Blanketing

Blanketing of tanks for fire protection should be considered if ambient temperatures warrant this (t>30°C). However, exothermic polymer formation is prevented by oxygen, so a minimum level of 15 ppm of dissolved oxygen is recommended. P-TBC should be added at a level depending on the residence time, but minimum at all times to be 5 ppm, to prevent subsequent poly-peroxide formation.

Fire Protection

The provision of fire protection systems eg. foam should be considered where appropriate. This includes water spray systems to isolate from other fires near the tank.

Earthing

Adequate provision should be made to allow dissipation of static electricity.

Internal Coating

Internal coatings are not required for styrene storage tanks, but can help to minimise polymer formation. Inorganic zinc silicate linings can be used. If a tank lining is used, it is important to ensure that a satisfactory tank earthing arrangement is provided.

5.5. Relief Valves

There should be a rigorous procedure for regular checking for signs of polymer formation.

6. Instrumentation and Monitoring

Level indicators and level alarms are advised to prevent tanks overfilling. Consideration should be given to extra high level interlocks to shut off the tank feed.

Pressure and temperature indications are also advised and should be monitored regularly.

An interlock of high level alarm with unloading pump shutdown is recommended.

7. Piping

Carbon steel, stainless steel may be used.
All low points should be provided with drains. Blanks should be fitted to open ends.

8. Pumps

Centrifugal pumps are preferred for styrene service. For environmental considerations double mechanical seals with styrene-compatible antifreeze flush are preferred.

9. Valves

Gate, globe, angle or ball valves may be used in styrene service. Stem packing should be graphite-based coil, modified PTFE, or equivalent. Bonnet gaskets may be soft iron, flat asbestos or spiral-wound. For ball valves, Teflon seats are acceptable.

10. Hoses

The use of hoses should be avoided, but if needed for loading or unloading operations, they should be styrene-resistant line armoured austenitic stainless steel flex hose or equivalent. Hoses should be inspected by carrying out a pressure and conductivity test at least every 12 months.

CEFIC
Avenue E Van Nieuwenhuyse 4
B- 1160 Brussels

Patrick Detournay
T +32 2 676 72 05
E pdt@cefic.be