December 30th, 2010
In most instances in life we describe things in approximate terms. We describe colours using the primary spectrum, the sky is blue, the sand is yellow etc. In most cases this is acceptable as people have shared common experiences and so have an understanding of what you mean. However, to anyone who works with colours such as an interior designers such basic descriptions are useless and it is necessary to be much more specific when trying to specify a colour especially if repeatability is of the essence.
The same principle applies with engineering and components such as pipe fittings and flanges. For example, there is a difference between a pipe and a tube. To most people these are the same things but in practice they are very different. A pipe is a general term used to describe a cylinder used to carry fluids or gases. A tube however is a much more specific item with tighter engineering tolerances. Both can be specified by nominal bore dimensions but a 25mm pipe will not actually measure 25mm across the inside diameter or the outside diameter whereas tube are specifically measured according to inside diameter or outside diameter as well as wall thickness.
This may seem like semantics but it has a serious aspect as if you have to specify a replacement section it is important that the bore and wall thickness match the existing installation. At Chemipetro we manufacture pipe and pipe fittings in many sizes and thicknesses so you can be sure to get the right part.
Tags: fittings, Flanges, Pipe Fittings, Pipe Flanges
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December 27th, 2010
At Chemipetro we manufacture a range of pipe fittings and flanges which are sometimes very complex designs requiring special machining techniques. We also manufacture the most basic of pipe fittings such as bends. However, it would be a mistake to believe that even such simple units do not require special process.
Anyone who has tried to form a bend in a pipe will know that it is not a simple matter as would first appear. If force is applied to a straight pipe then the unequal forces on the inside and outside of the bend will cause the pipe wall to distort and collapse.
To prevent this happening, it is necessary to use special techniques to bend a pipe and these vary depending on the size of the pipe. For small pipes it is possible to bend the pipe around a former. This supports the inside of the bend and prevents it deforming. It also ensures that a regular uniform bend is formed. Whilst this method works with small bore pipework it is more difficult to bend large diameter pipes as are more commonly used in the petrochemical industry
For these larger pipes a technique called induction bending can be used. Here a section of the pipe is heated using electrical induction coils and the pipe is bent slightly. The section is then immediately cooled to set the bend. The pipe is moved forward and the process repeated. In this way the bend is formed in small increments. This process works well with materials such as duplex stainless steel which are otherwise difficult to work.
Tags: Duplex, duplex stainless steel, Flanges, Pipe Fittings
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December 24th, 2010
At Chemipetro we have developed a wide range of specialist pipes, pipe fittings and flanges to cope with the many technical problems encountered in the petrochemical industry. These are manufactures from specialist steels such as duplex and super duplex stainless steels as well as other more exotic alloys to cope with the rigors of the more demanding environments such as salt water and corrosive chemicals.
However, technological innovations in other fields have also discovered that the products we manufacture are suitable for other applications which were never envisaged in the original product development.
One such application has been found in the electricity generation industry. For many years oil has been used as a fuel source in power stations and the handling of the fuel is the primary application for the products we manufacture. However with the spot light now turning also to what happens after the fuel is burnt, new applications are being found.
When fossil fuels are consumed in boilers, one of the products of combustion is sulphur dioxide. When this combines with water vapour in the atmosphere the product is acid rain. To prevent this happening the exhaust gases are cleaned by a process called Flue Gas Desulpherisation (FGD) to remove these products of combustion. This process however produces hydrochloric acid which of course is itself very difficult to deal with. Fortunately, one of the few materials which can cope with this is super duplex stainless steel and so the technologies developed for one use find a wider application.
Tags: Duplex, Pipe Fittings, Super Duplex, super duplex stainless steels
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December 21st, 2010
The petrochemical industry has required the development of specialist pipe fittings and pipes and flanges over the years to meet ever more demanding requirements. This has also led to the adoption of specialist materials such as super duplex stainless steels. These materials are none the less relatively straightforward to work and can be cut and welded in the normal manor. However, we at Chemipetro also manufacture parts from specialist materials that required more demanding techniques to work them.
Once such specialist material is titanium. Known as the space age metal, Titanium is very strong but has a low density compared with iron. In fact, it has the highest strength to weight ratio of any metal. It is also extremely resistant to corrosion from sea water, chlorine and even nitro- hydrochloric acid. These all go towards making it a suitable material for those extremely tough situations.
It is, however, its very toughness that can be a problem as it takes specialist techniques to work it. To weld titanium requires careful preparation to ensure that there are no contaminants on the weld surface. This can be done with steam cleaning or an alkaline dip but gloves must be worn as even chlorine from skin can cause contamination that will ruin the weld. The weld site should then be warmed to remove all traces of moisture. Finally the weld must be carried out in an atmosphere of pure Argon, and not just on the front but on the back of the weld as well.
A well done titanium weld will have the appearance of frozen mercury and will be shiny and reflective.
Tags: Flanges, Pipe Fittings, Super Duplex, welds
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December 18th, 2010
The concept of flanges is very simple. They allow two sections of pipe or pipe fittings to be joined together. Unlike a welded joint they allow the connection to be dismantled for maintenance or replacement. The fact that they can be dismantled however is also the root of their problem.
A welded joint produces a connection which is done correctly makes the pipe continuous and therefore it cannot leak. Flanges however consist of two flat plates that are bolted together. No matter how perfectly they are manufactured or how carefully they are fixed to the pipe there will always be some miss-alignment or distortion when the flanges are bolted together and this will mean a leak especially at high pressures.
To prevent this, a gasket is introduced between the two flange faces. The job of the gasket is to deform as the two flanges are bolted together and take up any irregularities. It is still important, however that the flange plates are as parallel and as perfect as possible as the amount of distortion the gasket can absorb is limited.
There are many different types of gaskets that can be used depending on the pressure that the joint will be exerted to from simple plate gaskets, to spiral would gaskets and ring gaskets. These last were especially developed for the high temperature and pressure applications that can be found in the petrochemical industry.
At Chemipetro we manufacture flanges with varying face types including flat face, raised face and ring type to ensure you can always get the right type.
Tags: Flanges, gaskets, Pipe Fittings, welded joint
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December 15th, 2010
As has been demonstrated in not too long ago in the Gulf of Mexico, failure of a pipeline in the petrochemical industry can have very severe consequences. This not only applies to well heads but to all aspects of pipelines required to transport hazardous substances.
In recognition of this fact the Pipeline Safety Regulations 1996 require that anyone intending to construct a pipeline must submit for scrutiny a complete package of information on the proposals for scrutiny and approval by the Health and Safety Executive.
As well as details of the operators, the route of the pipeline, details of what is to be conveyed and its operating parameters such as temperature, pressure and flow rate, the submission must include full details of the materials the pipeline is to be constructed from including the length, diameter and wall thickness of the pipeline itself.
This may not be down to the level of what type of pipe fittings are to be used but will set the standards as to what material they are constructed from such as duplex stainless steel. It will also note what provision is made for maintenance requiring sections to be dismantled and therefore constructed utilising flanges.
At Chemipetro we manufacture pipe fittings and flanges from specialist materials so that the pipeline designer can select fittings to meet the design requirements. We can also provide a full quality dossier consisting of quality plans, 3.1/3.2 certificates, letters of conformity and heat treatment charts to ensure that the pipeline operator can submit the necessary full supporting documentation for any proposal.
Tags: Flanges, Pipe Fittings, pipeline specifications, pipelines
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December 12th, 2010
Anyone who has a car knows that if it is not regularly serviced then the chances of it breaking down at some inopportune moment are greatly increased. The same applies in industry and to keep a complex machine or system running properly it needs to be regularly maintained.
Maintenance is something that the pipeline designer must fully take into account as one of the first principles when setting out the line runs. For a system to be able to be cleaned and maintained it needs to be able to be readily dismantled and there needs to be enough access for operatives to be able to get to the specific plant to do this.
The first parts that need to be considered are operational equipment such as valves and pumps. These will fail in service at some time and therefore need to be readily removable. To achieve this, these parts need to be connected into the pipelines using flanged connections. By using flanges rather than welded connections these pieces of equipment can be readily dismantled by undoing a few bolts.
However, sometimes it is necessary to dismantle further sections to allow better access. Here flanges should be fitted to pipe fittings as well so as to allow whole runs of pipe to be readily dismantled. This is more unusual as these sections are usually welded together.
At Chemipetro we manufacture various flanges in a range of sizes and materials because although these are only jointing pieces it is important to select the right one for the specific job in hand.
Tags: flanged connections, Flanges, Pipe Fittings, pipelines
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December 9th, 2010
Whilst pipeline designers will know the precise details of the mediums the pipeline is to transport, such as pressure and temperature and corrosive effects, it is not always possible to foresee the external influences that an installation may be subjected to. However, this is one of the fundamental principles that must be taken into account as set out in the Pipelines Safety Regulations 1996.
These regulations specifically state that a pipeline must be designed such that ‘it can withstand the external forces and the chemical processes to which it may be subjected’.
Some external forces cannot be predicted whilst others, such as mechanical damage, can be assumed even if the extent of the force cannot be entirely quantified.
There is, however, one external force which is well understood and can be allowed for in the design. This is the force exerted on the pipeline due to thermal expansion. As an example a 30metre length of stainless steel pipe which has its temperature raised from 0ºC to 100 ºC will lengthen by approximately 43mm. This rate of expansion can cause severe strain on joints at pipe fittings and flanges as well as fixing points.
This expansion must be taken into account by including expansion loops where the pipeline is allowed to deform in a controlled manner.
At Chemipetro we manufacture flanges and pipe fittings from specialist materials so that the pipeline designer can select fittings that can not only withstand the internal forces but will cope with any external force that is applied.
Tags: Flanges, Pipe Fittings, pipeline, stainless steel pipe
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December 6th, 2010
It would seem a pretty obvious statement that a pipeline must be able to withstand the fluids that it is actually going to transport, but this is one of the key principles set out for pipeline designers in the Pipeline Safety Regulations 1996.
No one would deliberately set out to design a system that was ‘not fit for purpose’ but this can be the outcome if full consideration is not taken as to what the long term effects of a particular medium will be on the pipeline through which it runs. Engineering history is full of instances where existing methods and materials have been applied to new technologies only to find that what used to be adequate is now not so and in the petrochemical industry in particular a system failure can lead to catastrophic results.
Duplex stainless steel was developed where greater strength was required than was available from ordinary austenitic stainless steels. When even further resistance to corrosion was required super duplex stainless steel was developed with a higher chromium content. These changes were made to ensure that the pipes and pipe fittings made from these materials could withstand the rigours of the new applications they were being asked to cope with.
With future development such as the production of new bio fuels rapidly happening there will be greater pressure to develop more resistant material to cope with these new fluids.
At Chemipetro we manufacture flanges and pipe fittings from specialist materials and look to develop new products so we can always be sure we can get you the pipe fittings and flanges you need that are made from the right stuff.
Tags: Duplex, Flanges, Pipe Fittings, stainless steel duplex
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December 3rd, 2010
Under the heading ‘Design of a Pipeline’, the Pipelines Safety Regulations 1996 state three guiding parameters in the design of any pipeline. These include that firstly the pipe must be able to withstand any forces that arise from its operation, secondly it can withstand the fluids it is actually transporting and thirdly it can also withstand any external forces or chemical processes to which it may be subject.
These seem pretty fundamental design requirements, but it should be considered that the regulations were written because at some time in the past someone did not design a pipeline in this manner and it failed in service.
The first requirement takes into consideration the working pressures under which a pipeline will operate. This will determine the types of pipe fittings and flanges that will be employed. Some flanges, such as swivel flanges, may be easier to install but may not be rated to cope with the pressure. This requirement also works in the designers favour as the pipeline does not all have to be installed to meet the highest pressure but where there is a pressure reduction in the line the pipe fittings used can also be of a simpler type.
An example of this is the fittings required to meet the high pressures at a well head have to be of the highest standard but further along the pipeline where the pressure is reduced, different types of fittings can be installed.
At Chemipetro we manufacture a wide range of flanges and pipe fittings to all standards so we can be sure to find the one you need.
Tags: Flanges, Pipe Fittings, pipes, swivel flanges
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