Continue of Part 3 - Dry-out
4. Chemicals loading of vessels
This specification addresses the loading of process vessels with Raschig/Pall Rings-type packings, molecular sieves and desiccants, ion exchange and demineralization resins.
Whenever such type of material must be loaded on site, a loading procedure should be required from the patented Supplier, and for some products one of his representative should attend the loading operation.
As part of the commissioning activities, the preparation and supervision of these operations should be carried out by the Commissioning personnel.
However, in case the representative of the Vendor is not available on site, the Commissioning should issue detailed procedures and carry out the operation, in line with the guidelines given hereafter.
4.2 Preliminary inspection
It is of primary importance to inspect the vessel before loading. The inspection should concentrate on the following points:
- Conformity of the vessel to the project drawings and specifications, but also to the patented Supplier drawings and specifications.
- Quality of the internals: if some internals are installed during or after the loading operation on they should be inspected at their storage location. The inspection of the internals should consist in verifying that:
- The material conforms to specification (mesh, trays, distributors, joints, baskets, etc.).
- They are in conformity with the drawings (shape, size, holes, etc.).
- They are installed in accordance with the drawings. Special attention should be paid to the internals arrangement (distribution pipes/boxes, for instance), the horizontal trays, the position of the joints, the tightening of bolts and nuts.
- Whenever the trays have to conform to a leak specification, they should be leak tested, by establishing a water level on the trays, that should be surveyed during a certain period of time.
- The equipment must be perfectly clean and rust free. This is also applicable to the vessel itself.
- If internal coating is required, check the coating quality.
- In the same way the product to be loaded should be inspected to assess its condition, storage conditions and conformity.
4.3 Loading preparation
The loading preparation includes:
- The organization of transportation and lifting of the material to be loaded
- The preparation and installation of the equipment necessary to perform the operation: platforms, funnels, hoppers, loading socks, ladders, lighting, ventilation means, safety protective equipment, e.g. breathing protections, rain protections if necessary, rope, buckets, etc.
One person should be nominated Loading Leader and should be responsible for the loading preparation and operation.
4.4 Loading operation
There are several ways of loading, the three most common ways of loading are the following:
- Hand loading
- Sock loading
- Loading with vessel full of water.
As a general rule, free fall in the vessel of the material to be loaded is forbidden. It should be accepted only if requested by the Manufacturer's representative or if clearly specified in the Manufacturer's procedures.
4.4.2 Hand loading
The material should be lowered inside the vessel either by hand (buckets) or by a crane (hopper with a manual sliding valve at the bottom) and spread by hand by the personnel inside the vessel.
This way of loading can be used on any type of product, but the process is rather slow and therefore it is applicable only when small quantities are concerned.
4.4.3 Sock loading
A funnel should be installed at the top opening of the reactor. It is recommended to equip this funnel with a slide valve. A canvas tube is clamped on the funnel outlet and inserted in the reactor. This tube is known as "sock". To overcome the problem of sock plugging large diameter socks (10 cm and above) should be used. Fire-fighting hoses are perfectly suitable.
Two hoppers should be used to carry the material to be loaded from the ground level to the vessel top (one hopper is filled up on the ground while the other one is used to transfer the material). Their content should be dropped into the funnel. The personnel inside the vessel should hand control the flow of the product (on the sock) to avoid free fall and spray it by moving the sock around.
The sock should be shortened regularly according to the level increase, but always with no excessive drop of the material. This is an effective method for loading as Experience shows that several tons can be loaded per hour.
4.4.4 Loading with vessel full of water
This method is applicable mainly for ceramic rings and Raschig/Pall rings packings. It should be strictly forbidden for any product that can be affected by water (all catalysts, desiccants, resins, molecular sieves).
Fill the vessel with water and charge the rings or packing via the top nozzle. In this way the material sunk gently into place without fear of cracking.
If this method is adopted make sure the vessel concerned can withstand the water load and the pressure of the static head of water.
4.4.5 Special precautions during loading
Some fragile material may not withstand direct stepping. In this case people inside the vessels should stand on boards or plates that should be rearranged as often as necessary to match the level increase.
It is of upmost importance not to forget anything inside the vessel (helmets, boards, rags, tools, etc.).
It is therefore necessary that a strict control be made at the vessel entry to ensure that all that was introduced in the vessel should be recovered at the end of the operation. Several methods can be used: numbering, marking, listing, etc.
Safety precautions have to be defined and strictly applied. They should differ following the type of product and vessel. The safety precaution should be listed at the preparation stage and all necessary material supplied accordingly.
If the material is to be loaded to a given height in the vessel, or if there is an interface level between two different products, the level on the vessel walls should be chalk marked early enough to avoid trespassing it.
4.5 Completion works
When the loading operation is completed, all vessel top internals should be installed (tray, distributors, etc.) and where satisfactory the vessel should be closed using new gaskets/joints.
A loading sketch should be issued. This loading sketch should indicate the actual levels of the material(s) and the quantities loaded (weight and/or volume). To establish the loading sketch, an engineering drawing of the vessel should be used.
The loading procedures, with support drawings and sketches, all reports and results should be filed in the corresponding subsystem Commissioning Dossier.
Each loading operation should also be supported by a specific Commissioning loading report form.
Continue to Part 5: Inert Gas Purging