In petrochemical and Oil&Gas plants, as well as in refineries, on/offshore rigs, chemical plants and process systems, the components may be subject to high pressure, changing temperatures, aggressive substances and vibrations. Therefore, if only one of the components doesn’t properly work, not only a breakdown may occur, but also a plant shutdown, dangerous leaks, expensive maintenance costs and safety risks may arise.
Being able to choose the best components of a plant is a strategic element to ensure high performance and operational continuity in the most complex industrial plants.
In this regard, the kind and the material choice cannot be done only referring to a catalogue. It is essential to rely on reliable and experienced partners and consider some aspects that will be examined hereunder.
In today’s edition, we will focus on fittings as essential components to link the different parts of a system.
First of all, it is to be said that any decision must be done on the basis of a structured technical evaluation.
The first point to clarify is the kind of substance flowing in your plant. Is it a fluid, acid gas, sea water, chemical substances or something else?
The second element to put attention on is the system working pressure and the temperatures.
The third aspect to focus on is the application, and generally speaking, the external environment where the fittings will be installed: humidity, marine atmosphere, external agents must be evaluated.
Furthermore, it is important to know the required connection: welding, threaded or compression? Each of them meets different requirements.
Last, but not the least, it is crucial to take into account also the specific requirements set by the final user.
All these evaluations led to avoid under/oversizing and affect the setting of a budget for a specific project.
TYPES
We can start classifying the main fittings categories among those ones we supply.
Compression fittings, suitable for different kinds of plants; they are available in stainless steel and brass depending on the application. The twin ferrules option is the standard and ensures a reliable seal in case of vibrations. It is the most spread solution. As the name suggests, in this case the connection is made by compression of the elements without the need for welding.
Forged fittings are usually preferred for small diameters and for more severe applications since they very well resist to mechanical stresses and high pressures.
Welding fittings useful in case of permanent connections between tubes. They are widely used in energy and petrochemical plants especially when the project requires line continuity and a high level of connection integrity.
Threaded fittings often used in case of removable connections for high-maintenance areas
High pressure fittings (10,000 – 60,000 PSI) chosen together with the tube depending on the working pressure they must withstand.
In the end, there are also manifolds and valves to complete the line; they are added to purge the safety elements and simplify maintenance operations.
MATERIALS
As already said, the material selection always must not be a random choice. Wrong materials may cause serious damages. A proper material, on the contrary, provides long-term durability to the plants.
Starting from AISI 316L, it is the benchmark for instrumentation tubing both because it has got an excellent resistance to corrosion and it is the best solution in terms of quality/performance- price ratio.
Nevertheless, in marine and in case of chlorides, it is often preferred to select more performant materials in terms of resistance to corrosion. In these cases, material such as Duplex F51 or Super Duplex F55 are better.
In addition, for extreme applications, in case of high temperatures or highly oxidizing environments, the choice should be nickel alloys such as Hastelloy C276, Inconel 625, Incoloy 825 and Monel 400. Obviously, the upfront investment will be paid off in plant reliability and durability.
There is also a fourth possibility, that is brass or copper, but only for general applications and if they are compatible with the fluid flowing inside.
SUGGESTIONS AND COMMON MISTAKES
After having done all the necessary evaluations in terms of kinds and materials, it is important to take care to some aspects and to avoid some common mistakes.
First of all, you have to bear in mind that a good seal always depends on the correct hardness matching between the tube and the fitting. Furthermore, it is suggested to always use the same material for both the tube and the fitting to avoid corrosion materials. In addition, it is recommended to always hold the certificate of the material, the so-called 3.1 certificate, or, if requested 3.2 and know the heat number for the traceability of the product.
The important thing is surely to not choose only on a price basis. Obviously, the price could make the difference with the competitors, but it must be always associated to a good product quality and, in any case, the product must comply with the requirements of the project.
Another common mistake is to underestimate the delivery time especially in case of imported products for which nowadays longer delivery times have to be taken into account. In the end, it is forbidden to mix non-compatible tubes and fittings.
In this context, we are your reliable partner and unique benchmark for tubing, fittings and accessories in general. We supply all the necessary components to make a complete process line supporting you in the choice of the most suitable products for your needs.
Our offer includes forged, welding, threaded and compression fittings made of different materials depending on the availability and on the specific requirements. Surely, goods in stock can optimize faster stock rotation, before having checked the availability.
In the end, we have the ISO 9001:2015 certification for steel components trading which testify our commitment towards process quality and continuous improvement.