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Selection of Corrosion Coupon and Probe
In the industrial field, corrosion monitoring technology is an important part of corrosion control and a reliable and effective means. It monitors and evaluates the corrosion of equipment to provide effective corrosion data to support equipment maintenance and protection measures. This can timely detect problems, formulate maintenance plans, and improve the safety and reliability of equipment. Here we will introduce the two main monitoring technologies in corrosion monitoring: Corrosion Coupon and Probe
1. Definition of Corrosion Coupon and Probe
Corrosion Coupons: Corrosion coupons are pre-weighed metal specimens inserted into a pipeline, tank, or system to measure material loss over time. By analyzing weight loss after exposure, they help determine the corrosion rate and assess the effectiveness of corrosion control measures.
Corrosion Probes: Corrosion probes are real-time monitoring devices used to detect and measure corrosion activity in a system. They provide continuous data on corrosion rates using techniques such as electrical resistance (ER) or linear polarization resistance (LPR), allowing for immediate assessment and preventive actions.
2. Corrosion Probes Vs Corrosion Coupons
Corrosion Coupon and Probe are two widely used methods for monitoring corrosion in industrial systems. Each has its own advantages and disadvantages, making them suitable for different monitoring needs and applications.
Feature
Corrosion Coupons
Corrosion Probes
Monitoring Method
Periodic monitoring by measuring weight loss after exposure
Real-time, continuous monitoring using electrical resistance (ER) or linear polarization resistance (LPR)
Data Availability
Requires retrieval and laboratory analysis for results
Provides instant corrosion rate measurements
Installation
Requires periodic removal and replacement; may require system shutdown
Permanently installed with access fittings; allows online data collection without shutdown
Accuracy
Provides direct metal loss measurements but does not capture short-term variations
High sensitivity to small changes, detects corrosion trends early
Response Time
Requires weeks or months of exposure before corrosion data is available
Immediate detection of corrosion rate changes
Suitability for High-Pressure Systems
Traditional coupon retrieval often requires depressurization or shutdown, though retrievable coupon systems exist
Suitable for high-pressure environments, with some models allowing online retrieval
Durability
Metal coupons corrode over time, providing direct evidence of material loss
Probes may degrade over time and require periodic replacement
Cost
Lower cost per unit, but requires periodic replacement and laboratory analysis
Higher initial cost due to sensors and data collection systems
Maintenance & Retrieval
Requires manual retrieval, cleaning, and weighing for accurate results
Minimal maintenance; data collection can be automated
Application
Best for long-term corrosion assessment and inhibitor effectiveness verification
Ideal for systems requiring real-time monitoring and frequent data collection
3. EMT Order Information of Corrosion Coupon and Probe
1) Access Fitting Body
Model
EMT-CIPA
Access Fitting Body of Coupon, Injector, Probe assembly
– The material of Access Fitting Body
0
CS
1
316SS
2
316LSS
3
DUPLEX SS
The Type of Access Fitting Body
B
2″Welded（suffix “pressure rating” can be added to B）
F
2″ANSI Flange（suffix “pressure rating & sealing type” can be added to F）
-Tee Size- pressure rating & sealing type if flanged end
0
No Tee
1
1/4″NPT(F)Tee
2
1/2″NPT(F)Tee
3
3/4″NPT(F)Tee
4
1″NPT(F)Tee
5
Hole for 1/4″SWN Flange
6
Hole for 1/2″SWN Flange
7
Hole for 3/4″SWN Flange
8
Hole for 1″SWN Flange
-Protective Cover Type/ Material
0
No Protective Cover
Material
1
Without hole
CS or 0
2
With hole
SS or 1
3
Bleed Valve
DSS or 3
4
Bleed Valve, & Pressure Gauge
For Example：EMT-CIPA-0F600#RF-0-2/CS shows 2″ANSI 600#RF Flange Access Fitting Body in CS, no Tee, Protective Cover in CS with hole 0F600#RF: 0F_ Access Fitting Body is Flanged in CS , 600#RF _Size is 2″ANSI 600#RF , 0:No Tee 2: Protective cover with 1/2NPT(F) hole /CS: Protective cove material in CS
2) Corrosion Coupons
Model
CC
Corrosion Coupons
-Code
Plug Body Assembly
Pxxx
Type
Material
Sealing Material
0
No Request
0
CS
0
No Request
1
Hollow Plug Body
1
316SS
1
Viton O-Ring / PTFE Primary Packing
2
Solid Plug Body
2
316LSS
2
HNBR
3
DUPLEX SS
4
INCONEL
Type of Coupon Holder
SR
Fixed Coupon Holder for assembling rectangular coupon
AR
Adjustable Coupon Holder for assembling rectangular coupon
LR
Ladder Coupon Holder for assembling rectangular coupon
SC
Fixed Coupon Holder for assembling circularcoupon
AC
AdjustableCoupon Holder for assembling circularcoupon
-Pipe Size
x
Pipe Size in inch
–Coupon Size
A×B×C
Coupon Size in inch or mm
–Coupon Material
x
Grade
-Finishing of Coupon
0
Mill
1
Glass Bead
– Isolation Gasket
0
No Gasket
1
Nylon Gasket
2
FTFE Gasket
For Example：CC-P221-SR-6″-3″×1/2″×1/8″-MS1018-0-2 CC: Corrosion Coupons P221: Solid Plug Body in 316LSS Viton O-Ring and PTFE Primary Packing SR-6″:Fixed Coupon Holder for assembling rectangular coupon and for 6″pipe 3″×1/2″×1/8″:Coupon Size MS1018: Coupon Material 0: Finishing of Coupon is Mill 2: Material of Isolation Gasket is PTFE
For Example：EP100-B1-C1-T20-S0-A105-358 EP100 : Cylindrical Electrical Resistance Corrosion Probe B1: Body Material is 316SS C1: Connector Type: Standard connector T20: ER Element is 20 mil thickness (10 mil useful probe life) S0: No shield A105: Element Alloy Material is A105 358:Probe length is 358mm
