CN1146015A

CN1146015A - Outdoor intelligent sulfide stress corrosionc racking/hydrogenb rittleness sensibility monitoring instrument

Info

Publication number: CN1146015A
Application number: CN 95111971
Authority: CN
Inventors: 杜元龙; 张学元; 杜鹏; 魏炜; 程玉峰; 李桂芝
Original assignee: METAL CORROSION AND PROTECTION
Current assignee: METAL CORROSION AND PROTECTION
Priority date: 1995-09-06
Filing date: 1995-09-06
Publication date: 1997-03-26
Anticipated expiration: 2015-09-06
Also published as: CN1067767C

Abstract

The monitoring instrument for monitoring sulfide stress corrosion of metal consists of a sensor and a computer. The sensor consists of palladium silver electrode and metal oxide electrode in KOH solution and its signal is fed to the computer. The input parts of the computer include current-to-voltage convertor and A/D convertor and the computer judges sulfide stress corrosion of metal via the calculation with software. The merits include the contrast measurement with calibrated signal and the direct measurement of the sensor on the surface. The said monitoring instrument may be widely used in monitoring industrial pipelines.

Description

The corrosion cracking intelligent monitor

The present invention relates to the monitoring device of metal sulfuration stress corrosion cracking.

In a lot of industrial sectors, the inwall of the iron and steel device of production system usually is in and contains H ₂In the severe corrosive environment of S or acidity, cause the corrosion of iron and steel inside inevitably, the atomic hydrogen of corrosion induced, understand some and penetrate into iron and steel inside, in case the concentration of hydrogen surpasses a critical value, will cause metal strength to reduce, stress-corrosion cracking due to sulphide inclusion (SSCC) or hydrogen embrittlement (HE) take place, cause the related device blast, cause personal injury and enormous economic loss, also can cause the pollution of environment, repeatedly serious accident shows that SSCC/HE is one of corrosion failure of harmfulness maximum in the industry.

From in essence, the SSCC of device also is a kind of hydrogen-induced corrosion crack (HIC), because H ₂The HS of S and its ionization ^-, S ^2-In the strong characteristic absorption of steel surface, make the atomic hydrogen of the cathodic process generation of corrosion be adsorbed on steel surface, hinder the process that atomic hydrogen is combined into hydrogen molecule, produced the concentration gradient of atomic hydrogen as a result between steel surface and its inside, under this concentration gradient effect, the atomic hydrogen on surface is diffused into iron and steel inside, penetrate in high dislocations of defective or the space, and be accumulated in stress and concentrate the position, cause the toughness of iron and steel to descend, fragility increases and causes the delayed fracture of iron and steel under the tension stress effect.

At present, also be not specifically designed to the instrumentation of monitoring iron and steel device generation SSCC/HE danger both at home and abroad, though the atomic hydrogen infiltration rate detection instrument of some commodity-type is arranged in the world, pressure type hydrogen detection instrument for example, " patch formula " hydrogen detection instrument, " barnacle formula " hydrogen detection instrument etc., but the shortcoming of their maximums is, hydrogenation electric current value that these instruments are recorded and used steel (do not comprise base material, weld seam and heat-affected zone) SSCC/HE danger takes place and connects in intensity/fragility in the corrosive medium of place and device, thereby, can't directly estimate the hazard level that SSCC/HE takes place with rapid judgment means only with these measured values.

For solving the deficiency of above testing tool, purpose of the present invention provides a kind of corrosion cracking intelligent monitor, utilizes the external sensor metal to be vulcanized the monitoring of stress corrosion cracking by electronic circuit and computer realization.

Technical scheme of the present invention is achieved in that the structure of external sulfuration stress corrosion cracking/hydrogen embrittlement susceptibility intelligent monitor is made up of external signal transducer and computing machine two parts, wherein signal transducer is to ooze suitable speed measurement sensor as signal element with elemental oxygen, has determined device steel and the variable concentrations H of sensor at different-thickness ₂Signal output level in the S solution, the structure of sensor is by shown in Figure 2, this sensor is a Cylinder shape, the outside is surrounded by the nickel housing, it is molten that 0.2M KOH electrolysis is housed in the housing, the molten center of electrolysis is placed with high-ratio surface high activity and the stable metal oxide powder electrode of current potential, connect with computing machine by nickel wire line, nickel housing outside is a cooling water system, end of probe is equipped with geometrical clamp, and the buffering mouth is housed between the termination, and a buffering mouthful outside is palladium-silver paper tinsel (Pd70Ag30) the contact utmost point, the centre is added with the silica gel sealing pad, the sensor other end is the teflon plug, and the center is a pipeline, and the centre is added with " O " RunddichtringO and connects with the nickel housing, the pipeline head is fixed with the double-sided socket that connects microsystem, and the end is a pipeline outer wall.

Computing machine connects figure as shown in Figure 1, and the front is a sensor, and sensor output connects with A/D breakout box input end by current-to-voltage convertor, and its output directly connects the 80C31 central processing unit.80C31 connects with machine internal memory 2764EPROM and internal memory 6264RAM, 80C31 while and external unit printer, and keyboard, display piece connects; Physical circuit is that CPU is that the output of 80C31 (as shown in Figure 5) address bus directly connects EPROM2764, RAM6264, address latch 74HC373, two-way multi-way switch 74HC245 and address decoder 74HC13B, two-way multi-way switch output connects display piece DMC162 (as shown in Figure 4), connect multi-way switch 74HC273 simultaneously, 74HC245, (U9, U15), A/D converter ADC0882, wherein multi-way switch 74HC245 (U15) output connects printer, sensor: output is by being input to A/D converter behind two-stage amplifier OP-07 and the LM35B, input end at converter provides standard voltage value simultaneously, converter output connects computing machine, because computing machine provides system software, has effectively realized the calculating to test data.Adopt signal scaling during calculating: mainly (UNS G10190 and UNSG11180 and tape welding seam material thereof are at H with steel to have determined two kinds of devices ₂Intensity/fragility in the S medium, and sensor signal is demarcated with this has been determined the signal of sensor and device with the corresponding relation between steel generation stress-corrosion cracking due to sulphide inclusion/hydrogen embrittlement brittle fracture danger, thereby has been demarcated the signal that records.

Its principle of work is to utilize Pd ₇₀Ag ₃₀Paper tinsel is worked as Pd70Ag as the sensitive electrode of oxidation atomic hydrogen ₃₀When the outside of paper tinsel contacted with the metal outer wall of equipment, because equipment is in and contains in the strong corrosive medium, negative electrode was separated out hydrogen and is infiltrated iron and steel inside, and atomic hydrogen will be from iron and steel to Pd like this ₇₀Ag ₃₀Spread in the paper tinsel, arrive Pd thus ₇₀Ag ₃₀The inside surface of paper tinsel, when two electric pole short circuits of sensor, the anodic oxidation of atomic hydrogen and the cathodic reduction of metal oxide just take place, and keep the total concentration of alkali lye in the sensor constant, the short-circuit current of the sensor that provides therefrom just can be used as the direct sign of atomic hydrogen infiltration rate.For example, suppose that the thick desulfurizer steel A of 3mm when operation, is determined by experiment, the signal that records when sensor (hydrogenation electric current, during I) greater than 80 μ A, this desulfurizer with steel to the stress-corrosion cracking due to sulphide inclusion sensitivity; As I during less than 50 μ A, desulfurizer is in a safe condition with steel; When I is positioned at 50-80 μ A, be in the state of potential danger, if when monitoring at the scene, when the signal of sensor was output as 30 μ A, desulfurizer was in safe work state; If when signal value output surpassed 80 μ A, then the danger of SSCC easily took place desulfurizer,, should or in time take other relative measures at desulfurizer inner interpolation corrosion inhibiter, to guarantee the operate as normal of desulfurizer for back two kinds of situations.

Software systems have been adopted in the microcomputer operation; For the field monitoring of implement device SSCC/HE susceptibility and on the spot assessment judge reliable data foundation be provided.

The present invention's advantage:

1. the hydrogenation electric current value that records of the sensor of determining by means of the inventor and device are with the corresponding relation between the intensity/fragility of steel, calibration measurements signal (hydrogenation electric current), thus make the hydrogenation electric current value that records directly be used for the SSCC/HE susceptibility of evaluating apparatus.

2. this monitor is attached directly to the device outer wall and uses the core component sensor employing Pd of monitor ₇₀Ag ₃₀Paper tinsel is as sensitive electrode.

3. adopt high-ratio surface, high activity and stable metal oxide powder electrode and the Pd of current potential ₇₀Ag ₃₀The primary signal that the stationary value of the short circuit dischange current density of the primary element that electrode constitutes in KOH solution is surveyed as inspection (prison) like this, can be simplified required potentiostat of common measurement and reference electricity level.

4. this monitor can pass through corresponding keyboard, and the initial conditions parameter: temperature, steel type, pipe thickness and sensor electrode area etc. can be suitable for the monitoring of the equipment SSCC/HE susceptibility under the different operating condition.

Detailed structure of the present invention is provided by following examples and accompanying drawing.

Fig. 1 is a corrosion cracking intelligent monitor controlling party block diagram;

Fig. 2 is corrosion cracking intelligent monitor sensor construction figure;

Fig. 3 is a corrosion cracking intelligent monitor sensor tube pipeline outer wall structural drawing;

Fig. 4 is a corrosion cracking intelligent monitor computing machine electrical schematic diagram;

Fig. 5 is a corrosion cracking intelligent monitor computing machine electrical schematic diagram.

The structure of sensor is by shown in Fig. 2,3, and it is labeled as: 1. 0.2MKOH electrolytic solution, 2. palladium-silver paper tinsel (Pd ₇₀Ag ₃₀), 3. oxide powder electrode, 4. nickel housing, 5. silica gel sealing pad, 6. nickel wire line, 7.O type circle, 8. buffering mouthful, 9. geometrical clamp 10. connects the double-sided socket of microsystem, 11. teflon housings, 12. cooling water systems, 13. pipeline outer walls.

When reality is used, sensor is attached directly to the outer wall of pipeline or equipment, by the keyboard input temp (℃), pipe thickness (mm), pipe wall material, sensor electrode area (cm ²) after, can carry out long term monitoring to this device, arbitrary moment all can directly show or at last with whole printouts as a result with the hydrogenation electric current value with to the judged result of SSCC/HE.

Claims

1. external sulfuration stress corrosion cracking/hydrogen embrittlement susceptibility intelligent monitor is characterized in that the structure of this monitor is made up of external signal transducer and computing machine two parts, and wherein signal transducer adopts palladium-silver paper tinsel (PD ₇₀Ag ₃₀) as the stable short-circuit current of metal oxide powder electrode in KOH solution of sensitive electrode and high-ratio surface, high activity and current potential as detection signal, this signal connects with computing machine by cable; The computing machine front is a sensor, sensor output connects with the A/D converter input end by current-to-voltage convertor, its output directly connects the 80C31 central processing unit, 80C31 connects with machine internal memory 2764EPROM and internal memory 6264RAM, and 80C31 connects with external unit printer, keyboard, display piece simultaneously.

2. by the described monitor of claim 1, it is characterized in that sensor is a Cylinder shape, the outside is surrounded by nickel housing (4), KOH electrolysis molten (1) is housed in the housing (4), is placed with the stable metal oxide powder electrode (3) of high-ratio surface, high activity and current potential in (1), connect with computing machine by nickel wire (6), nickel housing (4) outside is cooling water system (12), end of probe is equipped with geometrical clamp (9), and buffering mouthful (8) is housed between the termination, and buffering mouthful (a 8) outside is palladium-silver paper tinsel (Pd ₇₀Ag ₃₀) contact electrode (2), the centre is added with silica gel sealing pad (5), and the sensor other end is teflon plug (11), and the centre is added with " O " RunddichtringO (7), and the center is a pipeline, the pipeline head is fixed with the two-way plug (10) that connects microcomputer.

3. by the described monitor of claim 1, the CPU that it is characterized in that computer circuits is 80C31, EPROM2764, RAM6264, address latch 74HC373, two-way multi-way switch 74HC245 and address decoder 74HC13B are pressed in address bus output directly connection, two-way multi-way switch output connects display piece DMC162, connects multi-way switch 74HC273 simultaneously, 74HC245, (U9, U15), A/D converter ADC0882, wherein multi-way switch 74HC245 (U15) output connects printer; Sensor output is by being input to A/D converter behind two-stage amplifier OP-07 and the LM35B, provides standard voltage value simultaneously at the input end of converter, and converter output connects computing machine.