Engineering Details
Can stainless steel use at low and high temperatures?
Austenitic stainless steels are widely used at extremely low temperatures, down to -269°C (liquid helium), due to their lack of a sharp ductile-to-brittle transition in impact toughness. Toughness, measured in Joules (J), is tested by striking a small sample with a swinging hammer—the less it swings after impact, the tougher the steel. A minimum of 40 J is typically acceptable for most applications. Ferritic and martensitic steels exhibit a sudden drop in toughness over a small temperature range, often above -100°C, making them less suitable for cryogenic use. In contrast, austenitic steels retain high toughness (over 100 J) even at -196°C and resist transformation to martensite.
Cleaning methods for stainless steel.
Stainless steel is easy to clean. Washing with soap or mild detergent and warm water followed by a clear water rinse is usually quite adequate for domestic and architectural equipment. Where stainless steel has become extremely dirty with signs of surface discolouration (perhaps following periods of neglect, or misuse) alternative methods of cleaning can be used, as outlined below.
Does stainless steel corrode?
Although stainless steel is much more resistant to corrosion than ordinary carbon or alloy steels, in some circumstances it can corrode. It is ‘stain-less’ not ‘stain-impossible’. In normal atmospheric or water based environments, stainless steel will not corrode as demonstrated by domestic sink units, cutlery, saucepans and work-surfaces.
Is stainless steel non-magnetic?
This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1.
How To Choose Which Stainless Steel To Use?
What is the corrosive environment?
Atmospheric, water, concentration of particular chemicals, chloride content, presence of acid.
What is the temperature of operation?
High temperatures usually accelerate corrosion rates and therefore indicate a higher grade. Low temperatures will require a tough austenitic steel.
What strength is required?
Higher strength can be obtained from the austenitic, duplex, martensitic and PH steels. Other processes such as welding and forming often influence which of these is most suitable.
What welding will be carried out?
Austenitic steels are generally more weldable than the other types. Ferritic steels are weldable in thin sections. Duplex steels require more care than austenitic steels but are now regarded as fully weldable. Martensitic and PH grades are less weldable.
What degree of forming is required to make the component?
Austenitic steels are the most formable of all the types being able to undergo a high degree of deep drawing or stretch forming. Generally, ferritic steels are not as formable but can still be capable of producing quite intricate shapes. Duplex, martensitic and PH grades are not particularly formable.
What product form is required?
Sheet, bar, tube. In general, the austenitic steels are available in all product forms over a wide range of dimensions. Ferritics are more likely to be in sheet form than bar. For martensitic steels, the reverse is true.
What are the customer's expectations of the performance of the material?
This is an important consideration often missed in the selection process. Particularly, what are the aesthetic requirements as compared to the structural requirements? Design life is sometimes specified but is very difficult to guarantee.
Non-magnetic properties.
There may also be special requirements such as non-magnetic properties to take into account.
It must also be borne in mind that steel type alone is not the only factor in material selection.
Surface finish is at least as important in many applications, particularly where there is a strong aesthetic component.
Availability.
There may be a perfectly correct technical choice of material which cannot be implemented because it is not available in the time required.
Cost.
Sometimes the correct technical option is not finally chosen on cost grounds alone. However, it is important to assess cost on the correct basis. Many stainless steel applications are shown to be advantageous on a life cycle cost basis rather than initial cost.
Information Require When Choose A Filter Housing
What is the operating and maximum flow rate require?
Maximum flow rate 50m³/hr require. We will size a housing with flow rate average about 30% higher than 50m³/hr, a housing able to allow maximum flow rate 65m³/hr.
What is the temperature of operation?
Normally a 10″, 1 micron filter cartridge’s average flow rate is about 1m³/hr for cleaner and lower viscosity liquid.
What is the operating and maximum temperature of the liquid?
For ambient or below 50° C liquid, silicon seal can be use, but if the temperature is above 50° C, viton seal is recommended.
How viscosity is the liquid?
The higher viscosity, the lower flow rate allow for filter media.
What is the pH of the liquid?
For neutral or almost neutral liquid, housing with SUS 304 wetted part and silicon seal can be use. Strong pH liquid.
What is the operating pressure and maximum pressure require?
The higher pressure, the thicker housing body, flange and other parts require.
Liquid (media) analysis report available?
We can get data like pH, hardness, silica and other in the report. This will help to choose a right filtration media and filter housing.
What usage of the after filtered liquid?
For irrigation, 5 or 10 micron filter bag is good enough to remove particles which will clog the irrigation nozzles. In electronic industries, for wafer washing, the final filter housing may need in SUS 316L material and the filtration micron size may as low as 0.2 or 0.1 micron.
The filter housing to be use for which industries?
Final process of pharmaceutical or F & B industries may need SUS 316L material housing with sanitary connections. While SUS 304 is good enough for normal coarse filtration.
What is the filtration media (filter cartridge or filter bag) to be use?
We will propose according to your requirement, or we will recommend the right filter housing and filter media base on the above information.
What is the filtration micron size require?
We will propose according to your requirement, or will recommend the right micron size base on the above information.
What is the material of the piping which going to connect to the filter housing?
Either the above information require is complete or lack of information, this will help us to understand better and recommend the right filter housing and filter media.
Water Hammer
The Magnitude Of The Pulse
Water hammer can be analyzed by two different approaches, rigid column theory which ignores compressibility of the fluid and elasticity of the walls of the pipe, or by a full analysis including elasticity.
Effects And Mitigation
If the pipe is suddenly closed at the outlet (downstream), the mass of water before the closure is still moving forward with some velocity, building up a high pressure and shock waves.
Dynamic Equations
The water hammer effect can be simulated by solving the following partial differential equations where V is the fluid velocity inside pipe, Ï is the fluid density and Bm is the equivalent bulk modulus, f is the friction factor.
Possible Causes
Sudden valve closure, Pump failure , Check valve slam (due to sudden deceleration, a check valve may slam shut rapidly, depending on the dynamic characteristic of the check valve and the mass of the water between a check valve and tank).
Mitigating Measures
Water hammer has caused accidents and fatalities, but is usually less threatening. In many cases damage is limited to breakage of pipes or appendages.
Software
Software packages vary in complexity, dependent on the processes modeled. The more sophisticated packages may have any of the following features:
Cleaning Methods For Stainless Steel
Stainless Steel Designations
Water Hammer