Electrical Resistance
Electrical ResistanceThe Electrical Resistance (ER) probes utilize the relatively simple principle of an increase in electrical resistance produced by a decrease in the section thickness of a metallic conductor. 
Electrical Resistance
Electrical Resistance
Electrical Resistance
Electrical Resistance

 

 

 

 

 

The Electrical Resistance (ER) probes utilize the relatively simple principle of an increase in electrical resistance produced by a decrease in the section thickness of a metallic conductor. The increase in electrical resistance of a corroded element is measured in relation to that of a corresponding shielded reference element. The uncorroded reference element also serves to compensate for the effects of temperature changes on resistance. ER corrosion probes have been widely applied in oil and gas industry. 
ER corrosion probes have been made to replace “intelligent” coupons, facilitating a simple corrosion measurement without the need to remove the coupon from service at certain period. ER measurements are usually regarded as relatively insensitive; the probes generally do not respond rapidly to a change in corrosive conditions/change in corrosion rate. Sensitivity can be improved by decreasing the element thickness but only by compromising the overall probe life. Probe life corresponds to half of the probe element thickness by corrosion (tubular or strip element designs). For wire elements, the life span corresponds only to a quarter diameter loss. ER probes can be used in a wide range of environments and especially used in low conductivity and non aqueous conditions, where the use of the electrochemical techniques are generally unsuitable.
Caution: Conductive deposits such as iron sulfide or carbonaceous material on the probe elements will obviously distort the readings. The former is particularly relevant in sour oil/gas systems and certain forms of microbial corrosion, such as SRB attack.

EuropCorr® offers a wide range of high quality ER probes:
Flush/Projecting Probes (strip or “V” type element):
Flush element probes are available where it is particularly necessary to monitor localized wall effects, or where protrusion into the line would cause damage to the probe; for example, during pigging operations. 
The benefit of using this type of probe is that the element seal material is GLASS instead of traditional epoxy used for standard probes. The use of the glass seal material prevents deterioration of the element seal in most environments thus improving the probe life quite considerably.
Flush Probes are available both with fixed and adjustable length. The shape of measuring element can be strip type or “V” type, can be positioned flush with the inner surface of the pipe or vessel to avoid interference for pigging lines. 
Spiral Probes:
designed for long life under extreme conditions in oil and gas systems where a larger measurement surface area is desired and a shorter penetration into the pipe is required. This element geometry provides greater strength for high or turbulent flow environments and has a greater resistance to iron sulfide bridging. Due to a larger probe diameter, a shield is not required. The higher intrinsic resistance of this element design improves the reading resolution and the capability to measure low corrosion rates.

Tubular Probes:
The tubular probe element is comprised of a thin walled tube. Resistance readings from the sensing element are relative to a non-corroding reference element sealed within the probe body. Three probe designs utilizing elements of varying thickness permit usage in diverse situations. They provide a large surface area for measurement, have the fastest dynamic response to temperature transients, and are the least susceptible to the effect of any conductive deposits (such as Iron Sulfide) where present. Protective shields for the tubular element are available to protect the sensitive tubular element.

Wire loop element: 
These elements are generally more economical and available in a wider range of alloys than for other element forms. The element is comprised of a thin solid single length of wire, which overcomes any requirement of welding the element. Resistance readings from the sensing element are relative to a non-corroding reference element sealed within the probe body. The wire loop design is highly sensitive and performs well in locations subject to electrical or system noise. Element thickness offers longer probe life compared to other types. Two sizes of elements are available to suit requirements regarding sensitivity and desired probe life.

Selecting the correct probe sensitivity is very important to get the best results from your corrosion monitoring program in the most cost-effective manner possible. A sensitive probe will respond more quickly to process upsets than one with a greater span, but the element will corrode away and require replacement more quickly. Longer life elements are recommended when corrosion rates are medium to high and the objective of the program is to ensure that corrosion stays within acceptable limits rather than to rapidly detect process behaviour.

Probe length will be calculated by us based on the following information provided by the client:

- Position: access fitting position and monitoring position (TOL, MOL & BOL)
- Type of access fitting: Hydraulic or Mechanical system and flareweld or flanged
- Dimensions: pipeline size and wall thickness, additionally for flanged fitting: gasket gap and nozzle height (distance from top face of flange to external of pipe wall)

The EuropCorr® ER probes have 6 pin Amphenol connector, supplied with probe packing and probe o-ring, probe diameter 32mm, can be used with both two inch high pressure mechanical and hydraulic system, standard probes are designed for mounting through EuropCorr® hollow plug assembly.

Electrical Resistance
Electrical ResistanceThe Electrical Resistance (ER) probes utilize the relatively simple principle of an increase in electrical resistance produced by a decrease in the section thickness of a metallic conductor. 
Electrical Resistance
Electrical Resistance
Electrical Resistance
Electrical Resistance