When choosing a pressure gauge case, the following core factors need to be considered comprehensively:
1、 Core selection factors
1. Material
This is the primary factor determining the corrosion resistance and mechanical strength of the shell.
Carbon steel/ordinary steel: the lowest cost, but easily corroded. Only used in dry, non corrosive ordinary indoor environments. It is basically not applicable in harsh working conditions such as oil fields.
Stainless steel (such as 304SS, 316/316L LSS): This is the absolute mainstream choice in oil fields and industrial sectors.
304 stainless steel: has good resistance to general corrosion and intergranular corrosion. Suitable for most non corrosive environments.
316/316L stainless steel: Due to its molybdenum content, it has stronger resistance to pitting and crevice corrosion than 304, especially suitable for marine, high humidity, and chemical media environments containing chloride ions (such as oil fields and coastal platforms). It is the preferred recommended material for oil fields.
Plastic (such as ABS, polycarbonate PC): lightweight, resistant to general corrosion, but with poor mechanical strength, temperature resistance, and weather resistance. Mainly used in low pressure, room temperature, and non critical situations without danger.
Oilfield selection suggestion: Unless there are special circumstances, the default choice is 316/316L stainless steel shell to cope with common moisture, salt spray, and chemical corrosion in the oilfield
2. Protection level (IP Rating)
The IP rating indicates the degree of protection provided by the shell against the intrusion of solid foreign objects and liquids. This is a key indicator for measuring whether a pressure gauge can work stably in harsh environments.
IP54: Dustproof and splash proof. Can be used in indoor environments with a small amount of water splashing.
IP65: Dust tight, water-resistant. It has good dust and water resistance, and can meet the requirements of most outdoor and humid environments.
IP66: Dust tight, anti violent water spray. Can be used for decks, flushing areas, etc.
IP67: Dust tight, resistant to short-term immersion (water depth of 1 meter, 30 minutes). Can be used in situations where it may be briefly submerged by water.
IP68: Dust tight, resistant to continuous immersion. The highest sealing performance can be used for long-term underwater work.
Oilfield selection suggestion: For outdoor installation, areas with rainwater flushing, or areas that require regular use of high-pressure water guns to clean equipment, at least IP65 should be selected, and IP66 or higher is recommended. For underground tools, underwater equipment, etc., an IP68 rating is required.
3. Connection method
The connection form between the shell and the process pipeline mainly affects the convenience and sealing of installation.
Bottom Connection: The pressure gauge interface is located directly below. This is the most common connection method and the installation is intuitive.
Axial Back Connection: The pressure gauge interface is located directly behind and the dial is parallel to the pipeline. Suitable for panel installation, saving space, with the dial facing fixed.
Bottom Connection with Front Flange: Based on the radial connection, the housing has a front flange for securing the pressure gauge to the front panel with bolts for a more secure installation.
Back Connection with Rear Flange: On the basis of axial connection, the housing has a rear flange for fixing the pressure gauge from behind the panel, with the dial exposed in front of the panel and a neat appearance.
Oilfield selection suggestion: Choose according to the space and observation direction requirements of the installation location. For situations with high vibration (such as pump outlet), it is recommended to use a flange connection method to enhance fixation.
4. Size
The diameter of the dial. The larger the size, the easier it is to read the scale.
Common sizes: diameter 40mm (small size), 50mm, 63mm, 80mm, 100mm, 150mm, etc.
Selection principle: Choose according to the installation distance and reading accuracy requirements. For remote observation or key parameters, larger sizes (such as 100mm, 150mm) should be selected
In the oilfield environment, in addition to the general factors mentioned above, the following points must also be considered:
1) Corrosion resistance requirements:
Offshore platforms/coastal oil fields: In high salt and high humidity environments, 316/316L stainless steel shells must be used, and the surface is preferably passivated to maximize corrosion resistance.
Environment containing hydrogen sulfide (H ₂ S): This is of utmost importance for oilfield safety. Not only should the internal movement and spring tube of the pressure gauge comply with the NACE MR0175/ISO 15156 sulfur resistance standard, but the housing material also needs to meet this standard to prevent sulfide stress corrosion cracking (SSC) from causing the housing to rupture and causing serious accidents.
2) Mechanical protection and safety:
Seismic resistance: Oilfield equipment experiences significant vibrations. In addition to choosing a shock resistant pressure gauge (with an oil filled case), the structural strength of the housing itself should also be sufficient, and the connecting parts should be firm to prevent loosening or damage caused by vibration.
Explosion proof requirements: In hazardous areas where flammable gases may exist (such as wellheads, metering rooms, compressor stations), pressure gauges as potential ignition sources must meet explosion-proof standards for their casings.
Ex d (explosion-proof type): The shell is strong enough that it will not ignite external gas when an explosion occurs inside. This is the most common form of explosion-proof.
Ex e (increased safety type): Additional measures are taken on electrical appliances that do not generate arcs, sparks, or dangerous high temperatures during normal operation to improve safety.
Selection criteria: The pressure gauge housing of the corresponding explosion-proof level needs to be selected based on the division of explosive hazardous areas (Zone 0, 1, 2).
3) Environmental adaptability:
Climate: In extremely cold regions, the brittleness of the shell material at low temperatures needs to be considered; In high-temperature areas, it is necessary to consider whether the shell will affect internal components or burn operators due to high temperatures.
Simply put, for most application scenarios in oil fields, a standard selection is:
316 stainless steel material, IP66 protection level, radial with front flange connection, 100mm or 150mm dial diameter shock resistant and explosion-proof pressure gauge housing.
Before making a final decision, please make sure to confirm the specific safety regulations and environmental conditions in your area.