August 24th, 2010
Pipeline installations are designed to have a long economic life span. After all they are very expensive infrastructure investments which are costly to replace. Pipeline engineers therefore specify the best materials to meet this prolonged life expectancy such as duplex and super duplex stainless steels. They also ensure high quality engineered products for pipe fittings and flanges.
As a result of these high standards of material, the petrochemical industry generally has a good safety record considering the millions of litres of dangerous fluids and gasses that are processed each day. However, as witnessed by recent events in the Gulf of Mexico, even in the best run worlds things can go wrong.
The Pipelines Safety Regulations, recognise this fact and specifically states under item 12 that before any fluid is allowed to flow in the pipeline the pipeline operator must make specific provision for dealing with:
a) the accidental loss of fluids from the pipeline
b) defects or damage to the pipeline
c) any emergency effecting the pipeline
The pipeline operator must therefore have a safety regime in place that can deal with any type of emergency that may arise. This can be expensive if it is necessary to hold in stock replacements for each type and size of pipe fitting used in an installation.
Therefore in order to assist our clients to meet this obligation, we at Chemipetro offer a 24 hour emergency breakdown call out service. We also hold in stock a wide range of pipes and pipe fittings so that any problem can be dealt with as speedily as possible.
Tags: Flanges, Pipe Fittings, Pipe Flanges, Super Duplex
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August 6th, 2010
Quality control is a key asset for any manufacturer but particularly in the petrochemical industry where component failure can have serious results. Yet how do you ensure how components will perform and how can the uniformity of products be ensured?
Testing samples to destruction will give an overall indicator of how the design of a particular component will perform when exposed to high levels of stress. This confirms if the materials used are up to the task or if there is any weakness in the design. For example, if flanged joints or pipe fittings will perform as required when in actual use.
However, whilst this type of testing may be used to confirm the design of a component it is no use for ensuring the quality of the production run of components. For this it is necessary to use a test that does not actually break the component.
At Chemipetro we use a number of different techniques to ensure the quality of the pipe and pipe fittings we manufacture. One such technique is Liquid Penetrant Inspection.
Here the sample is washed with a liquid containing a special dye and left to soak. The excess material is then removed and a developer applied. When exposed to a high intensity or ultra-violet light, cracks or flaws in the material are visible. The advantage of this system is that it is quick to carry out and can be applied to no ferrous material as well.
These test procedure ensures that product quality is not something that is left to chance but can be assured across the product range.
Tags: flanged joints, Flanges, Pipe Fittings, pipe joings
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June 18th, 2010
We know that deep drilling causes problems for pipe flanges and other components. Heat, pressure and corrosion all combine to cause cracking, fatigue and failure unless the very best alloys are used. Yet even super duplex has a finite existence. In order to drill deeper, we first must know what we’re up against.
In the Gulf of Mexico are the world’s deepest untapped oil reserves, at the Tiber Oilfield. Already home to the deepest oil well in the world, BP now wants to explore deeper still – beyond the massive salt accumulations known to distort seismic waves, and way beyond the 6.7 miles drilled already, but will the pipe flanges take the pressure?
Much of what has been discovered so far has been down to the world’s deepest borehole – the Kola Superdeep, in Russia. Opened in 1972, it has revolutionised our knowledge of the Earth’s crust – which is a far more hostile place than geologists give it credit for. For example, at 7.5 miles down, drills encounter temperatures of 180°C, and pressures so high the rocks become “plastic” – solid to the touch, yet flowing like thick mud around the drill hole. Going past this point is impossible, with current technology.
The drilling apparatus Kola employs is very different to the rotating shafts of conventional deep-drilling rigs. Only the drill bit at the very end rotates, achieved by forcing drilling mud through the drill centre. As you can imagine, all the pipe fittings are specially made.
We at Chemipetro realise that few pipe fittings are as unusual as those at the Kola Borehole. Nonetheless, we will happily customise pipe flanges and fittings for your own projects.
Tags: Flanges, Pipe Fittings, Pipe Flanges, Super Duplex
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June 15th, 2010
Events in the Gulf of Mexico have brought home to us the hazards involved in deep water, offshore drilling. Yet it’s easy to forget that, all over the world are deep – sometimes miles deep – oil and gas wells performing perfectly efficiently. All the same, the pipes and flanges are regularly checked for signs of damage, and numerous sensors are installed to warn of possible geothermal trouble that might be brewing.
We know that deep drilling causes immense temperature and pressure stresses, as well as being a highly corrosive environment. This is why super duplex and similar high-strength alloys are widely used in deep water rig flanges.
Much of the information we have on the deep drilling environment comes from studies carried out at the Kola Borehole, in Russia. What’s been discovered has turned our dependable planet’s crust into a hostile, alien world.
Before the Kola hole was dug, researchers thought the crust was a benign series of rock interfaces. The heat and pressure started at the mantle, they thought. What they found instead was rock metamorphosed by heat and pressure so intense, it had forced out oxygen and hydrogen molecules to form water. Yet they also found intact fossil shells.
A little further, the rock turned to plastic, and the drill was so hot – way above the expected 100°C – that it had reached its tolerance. When it was withdrawn, the hole closed up. Yet the Earth’s crust had hardly been pricked.
The super duplex pipe flanges we supply at Chemipetro can stand up to most environments, although we’re not sure about changes to the laws of physics.
Tags: Flanges, pipe joints, Super Duplex, super duplex pipe fittings
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May 3rd, 2010
There has been much concern over environmental cracking in pipe fittings used in gas and oil plants, leading manufacturers to develop new alloys that are resistant to galvanic and chemical corrosion. We at Chemipetro supply pipe flanges and other fittings in a range of alloys, including Super Duplex, to minimise the risk of cracking. Provided these pipe fittings are correctly installed, and the usual maintenance and checking procedures are in place, corrosion is not usually a problem.
However, corrosion can be a problem in older petrochemical plants, where outdated metals are married to new, noble alloys. Then, galvanic or bimetallic corrosion can occur, owing to the electro conductive nature of the process fluids. The increasing interest in marginal oil fields i.e. fields with uneconomical reserves has made the problem more acute.
Marginal fields are of little interest to major oil companies, but are attractive to entrepreneurs because of their low operating costs and overheads. These low costs are often down to the poor quality of the flanges used in the original plant design. In addition, the process fluids used in marginal fields are often highly corrosive. If these are tied in to older pipelines, with pipe fittings that were designed for more mildly corrosive processing fluids, corrosion can occur at the joints.
Seawater (or “sweet” brine) still poses a big threat to pipe flanges, and many studies have been conducted over the years on its corrosive effects. The effects of “sour” brine, i.e. seawater contaminated with acidic chemicals, are especially of concern.
Tags: alloys, Flanges, Pipe Fittings, Pipe Flanges, Super Duplex
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March 25th, 2010
Flange shields are used to protect the faces, studs and gaskets on pipe flanges from atmospheric corrosion. Even with modern, highly resistant alloys, corrosion is still a problem – especially in refineries, gas plants and underground pipelines. To extend the life of modern pipe flanges, flange shields are therefore recommended. Designed to fit round raised face, full face and ring-joint flanges, they can cut maintenance costs considerably.
Many plant owners think it’s enough that they fit high-spec alloy flanges, such as those we supply at Chemipetro. However, environmental factors such as GICs (geomagnetically induced currents), UV radiation, dust and grime can play havoc with even the most up-to-date pipe fittings. Using shields can reduce these effects dramatically, leading to longer life and decreased chance of leakages and plant failure.
Flanges may be fitted with cloth or metal shields. The latter are available in a variety of alloys, including duplex. They are designed for high temperature, high pressure and highly corrosive environments. Shields fitted with spacing rods, which separate the shield from the flange, are especially useful where lateral and/or frontal sprayouts are a problem as they dampen the pressure.
Cloth shields are used in less extreme environments, or as extra “insurance” where high-spec flanges are already in use. They have the advantage of being cheap, and easy to fit. PTFE, polyethylene, PVC and polypropylene are the most common materials used.
Although the use of alloy shields can reduce running costs, especially on older plants, they should never be used over faulty flanges. Shields are not industry regulated the way pipe fittings are, and using them to “patch up” existing problems such as corrosion, cracking and leaking is both dangerous and illegal.
Tags: alloy flanges, Duplex, Flanges, Pipe Fittings, Pipe Flanges
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March 18th, 2010
Avoiding leaky flanges is paramount to safety at any industrial plant. Traditional ANSI flanges have been used for decades, and are still the most common choice for plant components at petrochemical plants. However, they are prone to leakage – something which needs to be addressed.
A number of improvements have been made to pipe fittings in recent years. For example, the new pressure connections, such as those we supply at Chemipetro, practically guarantee a leak-free performance. However, flange designs, for all their variety, have remained resolutely traditional. Their tendency to leak has been improved by modern technology, but not eliminated.
Conventional ANSI flanges are fitted by bolting two faces together, compressing a gasket and creating a seal. Integrity of the joint, and loading on the bolt, largely depends on the torque applied to the bolt when it is tightened.
The torques applied to pipe flanges are very specific. Therefore the proper procedures must be followed in order to avoid under or over-tightening and gasket leakage. However, even if the flanges are tightened exactly to industrial specifications, factors such as thermal expansion, internal pressures and fluctuating loads can cause movement between the flange faces.
The design of ANSI flanges means 50% of the bolt load is needed to compress the gasket, leaving only 50% to hold the pressure. Sudden, unexpected surges in line pressure, especially, can force the flange faces apart, placing stress on the bolts and creating an inefficient seal. Essentially, then, pipe flanges are inefficient.
Recent developments include patented compact flanges and API flanges. The latter withstand much higher pressures than traditional ANSI fittings.
Tags: ANSI flanges, Flanges, Pipe Fittings, Pipe Flanges
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March 16th, 2010
We at Chemipetro supply pipe flanges for the petrochemical industry in a range of resistant alloys, for example Duplex, Super Duplex and 6% Molybdenum (6Mo, or Moly 6).
These alloys are highly resistant to pitting, chloride corrosion and stress cracking, and offer excellent weldability and impact resistance. Duplex and Moly 6 pipe fittings are often used in the same installation, as they are highly compatible.
However, marine environments create particularly corrosive conditions for pipe flanges, which can defy even the most resistant of alloys. This was proved after the installation of the Sleipner A North Sea oil platform, in 1992/93. At the time, stainless steel alloys like austenitic molybdenum and super duplex were being widely deployed on seawater piping systems. For this reason, Sleipner A was fitted with 6Mo pipe fittings and 25Cr super duplex valves on the firewater piping system.
These alloys were qualified for use in seawater systems at a temperature range of 30 – 53 degrees celsius, which at the time was thought to be more than adequate.
However, just 18 months after installation, extensive leaks were discovered in sealed areas around flanges, valve components and threaded pipe fittings. This had been observed in other platforms. It was discovered that although the flanges performed well within the established temperature range, peaks above or below this had a catalytic effect on corrosion rates.
The answer was to fit a new galvanic resistor system to the platform, to withhold corrosion at extreme temperatures. Studies 10 years later show this is a highly efficient system, minimising further corrosion of flanges and pipe fittings.
Tags: Duplex, Flanges, Pipe Fittings, Pipe Flanges, Super Duplex
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March 2nd, 2010
Traditionally, oil rigs and workover rigs (which are used to increase production from established rigs) employ a vertical hoisting mechanism, or draw-works. This takes in or spools out a drilling line to raise or lower a travelling block – a system carrying the jointed drill-pipe assembly. The draw-works is connected to a derrick, which is connected to the ground. In this system, the weight of the tubular components is not transferred to the wellhead, and therefore stress on the flanges is minimised.
With the depletion of oil reserves new drilling methods, such as directional (non-vertical) drilling have become common. New technology allows the angle of bore to extend 90 degrees and beyond. For rigs like these, coiled tubing, rather than jointed pipe, is used.
While this offers numerous advantages compared to conventional drilling operations, there are drawbacks. The main one being that instead of a draw-works, an injector head is used. This is connected directly to the wellhead, via flanges or couplings. The wellhead is therefore subjected to considerable loads. As well as the weight of the tubing in the well, there are additional stresses generated by the twisting movements of the coil on the surface. The components affected include the Christmas tree joints, tee-joint pipe fittings, blow-out preventers, risers and casing flanges.
The method used to transmit the load back to the ground, rather than the wellhead, is a system of simple chains, which are ineffective. Now, rigid framework rigs are being tested. In the meantime, we at Chemipetro recommend rig owners buy the strongest flanges and pipe fittings they can.
Tags: 45 & 90 degree elbows, Flanges, Pipe Fittings, Pipe Flanges
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February 24th, 2010
Even well-manufactured pipe fittings can fail. Unfortunately, the problem is often one of unethical practice; something which, in heavy industry can lead to environmental disaster – or worse. Illegal cost-cutting and an inferior pipe flange is all it takes to spark a massive fire.
It appears there have been problems of a more subtle sort in Alaska, where federal warrants have been served on two oil facilities owned by the Chevron Corporation. Federal environmental regulators have reason to believe the company has been violating the Clean Air Act and knowingly making false statements about it since 2006. In 2006 Union Oil, a subsidiary of Chevron, was processing and storing crude oil from platforms in the Cook Inlet. The oil was then shipped to a Japanese refinery. The violations occurred when Chevron began shutting down vapour control units (VCUs) for its storage tanks.
VCUs are designed to capture and reuse vapours that would otherwise pollute the atmosphere. These are toxic, hazardous air pollutants known to cause serious health problems. Chevron’s statement to regulators in 2007 stated insignificant quantities had escaped, of around 2 tons a year. The true figure is nearer 200.
Why did they shut the units down in the first place? It appears they may have had no choice. We at Chemipetro are used to getting emergency call-outs to replace a faulty flange, but we would be shocked by, “improperly sized compressors; insufficient parts; fugitive vapours escaping; damaged and/or inoperable circuit boards; unsupported repair requests and various other problems.”
We’re pretty sure those problems would have included more than a few faulty pipe flanges.
Tags: Flanges, industrial pipe flanges, Pipe Fittings, Pipe Flanges
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