07/01/2004

Take the Hassle Out of Buying a Vessel

Purchasing new process vessels for the pharmaceutical industry is often a time consuming and onerous task. The industry is required to ensure that their new equipment meets with current legislation, operating procedures and approvals as well ensure that any ancillary equipment is fully integrated for successful operation.

For process engineers wishing to purchase a new vessel there are a number of procedures to go through before a vessel and any ancillary equipment is fully operational. These procedures can be very time consuming, and if not administered correctly can create unnecessary delays and hassle.

This article breaks these procedures down into categories and also indicates the best methods that engineers should adopt when purchasing new vessels.

1) Basic Design and Functionality

When designing a vessel / silo / bin for manufacture, the pharmaceutical engineer must consider what the vessel is going to be used for, and also where it will operate within the manufacturing facility. These early steps are important as they will underline what constraints will be imposed on the vessel further down the line. As it is sometimes difficult for a pharmaceutical engineer to understand the intricacies of a process vessel, at this stage receiving advice from a vessel engineer can enormously reduce the amount of time it will take to go through the design stages. By sitting down and meeting the pharmaceutical engineer, the vessel manufacture can ensure that all considerations are discussed. In this way, a lot of to-ing and fro-ing can be reduced.

As a check list, the following might be considered:-

• The size of the vessel needed
• The process requirements
• Ullage (spare capacity)
• Volume
• Location of the vessel for size constraints
• Whether the vessel will be mobile
• Contents of the vessel and the end usage of the stored chemical (for hygiene requirements)
• Working Pressures
• Working Temperatures

From this information the pharmaceutical engineer – together with the vessel manufacturer (if his expertise has been offered) can construct a simple design of the future vessel.

From this basic design the following will be determined

• Shape of the vessel
• Size of the vessel
• Material thickness of the vessel
• The surface / weld finish of the vessel
• Clean In process - CIP (if needed)
• Steam In process - SIP (if needed)

2) Hazop

Once the basic design has been created, the pharmaceutical engineer must then think about the vessel in terms of operation and what effects this will have on health and safety. A Hazop study is used to identify risks in terms of operation and how these risks can be eliminated.

Take for example a vessel operating at a temperature of 130ºC and at a pressure of 6 Bar which needed to be cleaned using the Steam In process. It would be vital to make sure that no personnel can open the manway in the vessel during the SIP process to ensure that in the event of an engineer opening the manway – a proximity switch will immediately shut down all equipment.

Another way of testing the vessel could be to create a 3D Solid Model. This is particularly important if the vessel is mobile. The centre of gravity can be determined to prevent tipping. In addition, the aesthetic appeal of the vessel can be greatly improved.

Again, if the advice of a vessel manufacturer has been brought in, the likelihood is that he has already advised the client on some of the dangers involved with the brief. By incorporating the knowledge of the vessel manufacturer into this stage, the pharmaceutical engineer can be certain that the hazop study will bring forward all potential hazards. The vessel manufacturer can also be tasked with the responsibility of completing the hazop study on behalf of the client if necessary.

3) Final Design

The aim of the final design is to incorporate the Hazop study into the basic design so creating the final design. The hazop study can reveal issues that were not considered in the basic design. This can mean that the basic design of the vessel can be changed in terms of functionality. For example, it may be determined that a vessel now needs to become completely drained so that a number of different chemicals can be processed in the vessel. Consequently, a CIP or SIP function may need to be added.

It is therefore imperative that the pharmaceutical industry carries out the hazop correctly. Without this, the vessel manufacturer cannot ensure that the vessel meets with current legislation.

At this point, the design should also start to include the design codes and structural calculations. Design codes are standards of construction guidelines that set down the parameters that can be used for calculation. For example, they will determine the thickness of the metal required when considering the maximum temperature or pressure during operation. It is the pharmaceutical industry’s responsibility to make sure that the design codes meet with the requirements of the vessel. Again, with the help of a vessel manufacturer, this task may not be as gruelling as it seems.


4) Manufacture to Required Standards

Once the final design is completed the vessel is then ready to begin its manufacture. From the final design a weld map is created. The weld map identifies all weld types needed throughout the vessel’s construction. The manufacturer also begins to list all the materials needed for manufacture. Each material will have its own material grade, code and specification – this will therefore ensure that the vessel is built to the required standards – indicated in the final design. In addition, before the manufacturing of a vessel commences the weld team must be prepared. To do this, the manufacturer must ensure that each member of the team is fully qualified to the appropriate standards. All technicians should be periodically tested by independent bodies on their quality.

Once a list of materials is drawn, it is the manufacturers responsibility to source and then purchase the material. It is imperative that all materials are certified to the relevant standards. To do this, the manufacturer must inspect all incoming material and note its arrival and conformance to specification.

Once construction is underway, it is imperative that the inspection process is continuous. For example, X Ray’s on individual welds can determine whether or not a piece was welded correctly and if there is a crack – potentially very dangerous.

Another factor that must be considered at this stage is the cleaning process of the vessel. Since hygiene is a very important consideration for the pharmaceutical industry, the vessel manufacturers must incorporate this into the process. Ideally, the cleaning process starts immediately and is ongoing throughout manufacture – particularly inside the vessel if it is small.

Once manufacture is completed, non destructive testing (NDT) can be carried out on the vessel should the customer or the design code request it. For example, the design code Asme VIII requests that 10% of all T welds are X-rayed in any one job. This Other NDT’s includel, Dye penetration, UV or Pressure Testing.

5) Third Party Inspection

As part of the manufacturers responsibility, independent bodies such as Lloyds and Zurich will be required to inspect the vessel before operation. They will be required to check the design, manufacturing and to also witness the testing. This aspect of the manufacture is the pharmaceuticals guarantee from a third party that the vessel has been manufactured to the required standards.

6) Quality Assurance of Manufacturing

The Quality Assurance (QA) are documents put together by the vessel manufacturers, which map the entire process of production. It is an ongoing process from the bill of materials through to the final inspection and lets the customer know where their products were sourced and how they comply with the design codes set out in the final design brief for example. Ultimately, it ensures that all the components that make up the vessels are checked, certified and recorded to the required health and safety standards.

Once the vessel has been Quality Assured it is then ready to be shipped to the customer. All the pharmaceutical engineer then does is to verify that the vessel supplied and noted in the QA are correct. Once this is completed, the vessel is ready for operation.

7) Assembly of Finished Vessel

However, unless all the ancillary equipment such as load cells, pressure valves, drain valves and mixers are also supplied and verified at the same time the vessel cannot be used. The finished vessel can only be completed once this equipment is sourced, Quality Assured and verified.

This stage is usually the most frustrating for the pharmaceutical industry, as often ancillary equipment may not integrate with the vessel. This sometimes creates delays which may not have been accounted for in the initial stages.

However, some vessel manufacturers such as Braby, in addition to supplying an advisory service from the initial design stages, will also source and install this ancillary equipment as part of the production package. This way, the vessel manufacturer can ensure that all the ancillary equipment goes through the same rigorous sourcing, testing and QA processes as the vessel. In addition, the vessel manufacturer can ensure that all ancillary equipment is fully operational and integrated with the vessel prior to delivery. On arrival at the factory, the vessel manufacturer can also be on hand to sort out any immediate teething problems.

This prevents unnecessary storage of the vessel at the pharmaceutical facility as well as unnecessary hassle. Often, vessels are delivered, however due to complications with the ancillary equipment are left redundant on the factory floor while many problems are sorted out.

8) Validation of the Package

Once the vessel is fully assembled, the process vessel and any ancillary equipment must be validated as a package. This is done by verifying that the original designs meet with what has been delivered.

Documentation of the package must also be produced in the form of a data book. This book will hold all information regarding the entire package from who welded the joints to where all of the materials were purchased. Ultimately it is intended to be a design, manufacturing and testing record. The book represents the foundations and basis upon which a technical file can be built to support voluntary CE Marking of the vessel, should there be a requirement to do so. If the vessel manufacturer has completed the entire project then it is his responsibility to ensure that data all equipment – including the ancillary equipment is included. However, if the pharmaceutical engineer has completed the project then he must ensure the data book is assembled with all the relevant information for future safety audits.

Should the vessel manufacturer provide the data book, the only responsibility the pharmaceutical manufacturer has, is to verify that the validation of the equipment is correct, and that what is supplied is clearly indicated in the literature.

The procedure of designing and buying a vessel needs to go through many stages before operation because of the inherent dangers associated with the processes that run through the vessel. Without the consistent aid of an expert, a pharmaceutical engineer may find that creating the designs, hazop studies and then sourcing ancillary equipment and installing it is very time consuming. By bringing all these components together and packaging them into a total solution for a pharmaceutical engineer – time can be saved as well as hassle.