Reduction of gas and oil pipeline failures using radiography inspection technique

doi:10.21203/rs.3.rs-3150326/v1

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Reduction of gas and oil pipeline failures using radiography inspection technique

https://doi.org/10.21203/rs.3.rs-3150326/v1

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The oil and gas sector faces a challenging predicament as the recurring issue of pipeline failures impedes progress. One such setback arises from corrosion that stems from Fe²⁺ Carbon steel pipelines. This corrosion leads to equipment wearing out prematurely, leading to potential environmental hazards caused by product leakages. This study investigated pipelines failures using radiography inspection method. Results showed that the smaller the pipe thickness, the higher the corrosion rate and a welding is likely to break where it failed before. This work confirmed that routine maintenance of pipelines is key to reducing product losses and environmental pollution with oil or gas leakages.

The continued escalation of pipeline failures remains an area of concern in the oil and gas industry. Process types of equipment are the most critical assets in the triangle of business operations because it contributes directly to operational costs and the company's profitability (Mutlaone, 2009). Plant availability is regarded as the most critical business objective everyone should strive to achieve for the organization's success. However, poor maintenance strategy results in safety events that endanger people and the environment. Toyota is a Japanese company that adopted the total production system. The total production system was adopted to improve the quality and eliminate and minimize defects in the production process (MacBride, 2022). In addition, unplanned maintenance reduces business profit. Moreover, operation management should reduce maintenance costs to advance people's safety, prolong the business's life span and protect the environment.

Poor risk management is the leading cause of pipeline failures in the oil and gas industry (Hopkins, 2012). Further, the slogan by engineers that “If not broken, why fix it?” indicate an attitude that reveal the importance of learning from near misses and through pipelines which are corroded. Corrosion remains an unresolved threat in the oil and gas industry.

For example, on the 20th of April 2021, at one of the plant, there was a fire and catalyst at the conical section of the hopper due to the pinhole on the plug valve body. In an integrated report for the year under 30 June 2021, it was highlighted that a few setbacks in commitment to achieving zero harm policy, occurred due two tragic workplace fatalities which were recorded respectively of the 2020 and 2021 financial years. In the same year, incidents related to fire, explosive and severity role (FER-SR) increased from 9.9–10.8% (Morgan, 2022). The company thus affected also shows commitment to the national energy sector by contributing 1.3MW to the South African grid to assist Eskom in meeting electricity demand.

The oil and gas industries must adopt the maintenance strategy used by nuclear industries to accomplish the nuclear renaissance. The Three Mile Island nuclear incident, Fukushima Daiichi and Chernobyl nuclear disasters all counted as examples. However, safety records remain excellent and the next generation of nuclear reactors were designed to avoid Chernobyl explosion disaster (Pokoha, 2018). According to (Mutlaone, 2009)the business asserts need a proper maintenance strategy to continue maintenance work at the Matumba power station that will prolong the equipment's lifespan to ensure effective operations. The state of the nation address 2023, delivered by President Cyril Ramaphosa, strictly focused on energy and minerals (Ramaphosa, 2023). In his speech, the president further articulated the Minister of Electricity appointment, which will focus on maintenance work at Eskom to reduce the spade of load-shading facing the country (Ramaphosa, 2023). President further explained the duties of the new minister, which emphasised the importance of smooth maintenance in power stations which will increase the company's turnover (Ramaphosa, 2023)

1.1 Inspection and maintenance

Maintenance management is divided into 3 categories, which are:

Reactive maintenance
Predictive maintenance
Preventative maintenance

Once the maintenance strategy is transparent, it makes it easier for the organisation to group business and maintenance objectives (Bhebhe and Zincume, 2020).

Maintenance work's most significant advantage is regarded as a safety barrier in business operations ( Yuan, Reniers, Yang, Bai, 2023). However, with the increase in demand for product quality, firms have to adopt a maintenance strategy. To ensure plant availability, the management must re-examine the maintenance scope, including service routine, periodical inspection and quality control (T.Y. Kim, Cha, Jung, Roh, Y. Kim, Jung, Yoon, Hwang, 2020). Optimization is utilizing fewer resources to yield more products, hence in maintenance, optimization will mean cost reduction in the plant (Franklin, Snider, Tronskar, 2003). (Avish and Sanya, 2020)Agreed that the business should start focusing on equipment quality control to achieve quality products by improving equipment maintenance. Any operating organisation's objective strictly depends on plant availability and productivity to meet customer demands (Mthembu, 2015). According to (Mthembu, 2015), plan maintenance reduces plant variable and fixed costs, directly affecting business revenues. The main aim of this report is to investigate pipelines failures using radiography inspection method, in the oil and gas industry.

2.1 Introduction

Non-destructive testing is a scientific discipline that has been used for over six decades to identify hidden flaws in oil and gas industry pipelines. Therefore, the organization must develop piping inspection methods and procedures to achieve a safe working environment.

Ultrasonic testing

In the family of non-destructive testing methods, a radiograph is known to be an effective inspection without affecting the pipeline (Ma,Tian, Zeng, Li, Song, Wang, Gao, 2021). It is done using the structure- electromagnetic radiation without damaging the equipment.

2.2 Mishaps and defects in the welding process

The author of this article has visited different oil and gas industries researching pipeline failures and found that most pipelines failed due to corrosion and erosion caused by Iron-based catalysts (Jacobs, 2016). Pipelines are mostly used in oil and gas industry to transport fluids ( Feng, Yang, Zhang, Zheng, Liu, 2021). Material failures are caused by corrosion and external forces surrounding the pipeline ( Feng, Yang, Zhang, Zheng, Liu, 2021). Previous studies by(Jamshidi and Davarned, 2021) and( Feng, Yang, Zhang, Zheng, Liu, 2021) both agrees to(Carvalho, Rebello, Souza, Sagrilo, Saores, 2008) where address the same issue of optimization of the pipeline because small cracks increase the danger of leaks that will result on catastrophic events. Therefore, conserving pipelines in oil and gas industries requires monitoring and evaluation methods of pipeline integrity to reduce the risks posed by harmful hazardous chemicals inside pipelines. The researchers have tried different types of methods in addressing the issue of corrosion of pipelines, alternating current field measurement probe, and the Monte Carlo calculation simulation. They have further performed the experiment using Guide wave (GW) to detect internal and external thickness in the pipelines (Bertoncini, Raugi, Turcu, 2008). The author stresses the importance of inspection parameters, which compromise pipelines, discontinuous, type of inspection and inspection range.

(Belkacemi, Benzerga,Berrikia, 2022) Summarises the four most common defects that occur in pipelines that decreases wall thickness, viz:

Corrosion,
Welding seam failures,
Stress corrosion,
Fatigue damage

This research is based in Secunda, Mpumalanga province of South Africa, approximately 90 km from Johannesburg. The location encompasses the largest coalfield found on the continent. While conducting this study, a factory and laboratory were utilized to analyse various samples collected, however, due to confidentiality agreements regarding their production and radiographs examination process, they will not be disclosed herein. All fifteen (15) samples studied were acquired from one particular plant and segregated according to construction material used for pipeline manufacturing purposes, specifically carbon steel because it proves cost-effective within the oil and gas industries.

The Radiation laboratory located in Secunda studied the thickness of pipes, specifically those with 2-inch schedules. Equipment calibration certificates were checked before sampling to ensure accuracy and safety measures were followed before obtaining samples from the plant. In order to safeguard personnel working within the facility, radiation-affected areas are calculated based on ALARA principle guidelines and secured with barriers to prevent interference by individuals. When utilizing Non-destructive testing techniques, the radiation intensity is determined using an inverse square law equation that is generally applicable.

\(\frac{{I1}^{2}}{{I2}^{2}}=\frac{{D1}^{2}}{{D2}^{2}}\) 1

I₁ and I₂ = intensity at positions 1 and 2

X₁ and X₂ = Distance from the source position 1 and 2

3.1 Sample collection

The study focused on pipelines of different diameters (2 and 8 inches) transporting the same product, where samples were collected weekly for three months with a constant mass flow rate. The pipelines were marked with white spray for future reference and the film used in the study was also marked before being transported to a radiation laboratory for analysis

3.2 Sample run

3.2.1 Gamma Radiography experiment

The experiments apparatus used to obtain radiographs, camera radiography 1196 Av 099 United Kingdom, Pretoria gamma tech, the radiation source was Iridium-192, and the winding gear must be long enough to ensure a 7.5 m distance, connector cable, and Pigtail connected to the shell [Source] and Film. The film was placed on the far end of the pipeline to create images by absorption process and further analysed in a dark room section of the laboratory. In summary, this means the radiation source was always on the opposite side to film in the pipe during task execution. The quality of the material was examined by gamma radiation interacting with the pipe.

3.2.2 Film Processing

Darkroom film processing after taken from a chemical plant and the room was equipped with safe light, which helps in film processing. Four tanks were used in the film processing; developer tank, rinse tank, fixer tank, and plain water tank. The main aim was to convert radiographic images into visible images. The film was placed in the developer tank for 5 minutes, and the solution set at temperature 35⁰C, 15 ml each of Sodium sulphate, Sodium carbonate and Potassium bromide were pipetted into 5 litre water tank. Then, the film was sent to the rinse tank to be washed for the remaining chemical from the previous tank for 10 seconds at the same temperature of 35⁰C. The third step was fixing for 10 minutes at 35⁰C, in this process, 10 ml of Sodium, Sodium Sulphite and Aluminium potassium bubble in water with 5 drops of Acetic Acid, this step was followed by washing for 15 minutes at the same temperature 35⁰C. The last step, which is very critical, is the drying process, which takes up to 30 minutes at a temperature of 57⁰C.

Testing techniques are different due to the number of equipment present in a chemical plant and also pipe sizes, to name a few:

Single wall single image _ Film inside -Source outside.
Single wall single image – Film outside - Source outside.
Double wall single image – Film outside - Source outside.
Double wall double image – Film outside - Source outside.

The first assessment is whether the pipe is less than or greater than 3 inches. Second is directly to the object, whether testing material/thickness/configuration. Thirdly where about in the pipe test to be done, for example, welding joint, forging, and assembled part. Fourthly type of discontinuity in the suspected area. Fifthly pipe failure usually occurs in critical and vulnerable areas, i.e., bends, welding joints, and assembled parts. Lastly, the type of film to be used is critical to achieving quality radiographs.

This research aimed to predict the decay rate and estimate the decay thickness of the pipeline. A gamma radiography experiment produced radiographs that display the pipe's remaining thickness.

Table 1

Laboratory and simulation results of pipes
Carbon Steel	Corrosive Products	Flow rate(t/h)	Week	Sample Thickness(mm)			Simulation
	Fe²⁺Catalyst Nitrogen N_{2 ,} Methane CH_3, Water H₂O	100lb/h		Diameter 8 and 4 inches (mm)		Decay-rate mm/h		Decay Thickness (mm)
Periodical inspection 1			1	4,5	2,4	0,05	0,09	1,83	3,59
			2	4,4	2,3	0,04	0,09	3,58	6,87
			3	4	2,1	0,04	0,08	4,94	9,52
			4	3,9	2,1	0,04	0,08	6,46	12,69
Periodical Inspection 2			5	3,8	2	0,04	0,08	7,92	15,27
			6	3,7	1,9	0,04	0,07	9,32	17,67
			7	3,5	1,9	0,04	0,07	10,48	20,62
			8	3,3	1,8	0,04	0,07	11,56	22,75
Periodical Inspection 3			9	3,2	1,7	0,14	0,07	12,78	24,74
			10	3,1	1,5	0,03	0,06	13,96	25,77
			11	3	1,4	0,03	0,06	15,1	27,49
			12	2,9	1,4	0,03	0,06	16,2	29,99
Periodical Inspection 4			13	2,6	1,2	0,03	0,06	18,01	32,99
			14	2,5	1,1	0,03	0,06	19	34,36
			15	2,3	1,1	0,03	0,06	19,67	36,65
			16	2	1	0,03	0,06	20	37,89

Table 1 summarizes all properties of the pipeline that were used to predict the decay rate and estimate decay thickness, sample was collected and analysed in the laboratory. However, there was slight thickness depreciation from the laboratory results. Furthermore, the Excel thickness simulation used a physics equation to predict the decay rate and estimate decay thickness.

The decay rate of 8 “in” and 4 “in” decreases slowly from 0.03 and 0.09, respectively, to 0.03 and 0.06. Figure 4 is the graph summarising the decay rate of two pipes under investigation, but the 8 “in” pipe from weeks 8 to 10 shows an aggressive increase. Both pipes' decay rates behave similarly, ensuring they use the same corrosive products.

Figure 5 illustrates pipes depreciation by increases in decay thickness, time is directly proportional to thickness loss in the pipelines. The 4 inch pipe loses more thickness as compared to the 8 inch pipe because the mass flow rate is the same, so the smaller the size, the higher the corrosion rate. In 16 weeks, the 8-inch pipe lost about 20 mm thick compared to the 37 mm thickness of the 4-inch pipe.

In radiation science, differential absorption is used as a principle, for example, more thickness absorbs less radiation in compares less thickness but transmits more radiation onto the film. Figure 6, below is the corrosion level because of product build-up or debris and the thickness reduction from 8.8 mm to 4.9 mm. The weld discontinuity noted on wormholes on the far right, T₄ bottom section also shows linear indication and a decrease in thickness from 3.8 mm to 2.4 mm. To summarize, the black portion shows less thickness than the white portion, which has more thickness increased by-product build-up. Therefore, the film will depend on or change the amount of radiation received.

Figure 6, weld discontinuities are one of the defects experienced more in the oil and gas industry. For example, the picture below shows poor welding quality with a 2.3 mm protruding bottom section on the right-hand side compared to the 2.7 mm and 2.7 mm bottom section left-hand side. Welding is likely to break where it had failed before.

This research shows that corrosive products are the biggest threat to pipelines' lifespan. Combining radiography inspection methods and simulation to predict pipeline failures is crucial to minimize incidents in the workplace. The other advantage of combining these two concepts is that it makes it easier to predict the conditions and estimate how much thickness the pipeline loses while in service and welding is likely to break where it failed before.

Developing a maintenance strategy reduces operational costs and safety events that create a safe working environment. Inspection and maintenance contribute to business revenue and customer satisfaction, once customers are happy, it is easy to retain them for the company's future.

Center for Applied Radiation Science and Technology (CARST)

Supervisor Permission to Submit Article for Publication

Name: Vusumuzi Mbizani	No: 26717654
Title: Reduction of gas and oil pipeline failures using radiography inspection technique
Qualification: Master in Applied Radiation Science and Technology			School: Natural and Agricultural Science
		Yes	No
I declare that the work contain in this article is my investigation and it never sent to any journal for publication		Yes
I agree to submission of this article for publication		Yes
Ethics and approval and consent to participate		No
Availability of data and material			No
Competing interests			No
Funding:DHET Bursary Scheme		Yes
Authors' Contributions: reduction of safety incidents in workplace
Acknowledgements: my sincere gratitude goes to Prof. Mathuthu		Yes

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No competing interests reported.

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Reduction of gas and oil pipeline failures using radiography inspection technique

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Abstract

Figures

1. Introduction

1.1 Inspection and maintenance

2. Non-destructive testing of pipelines

2.1 Introduction

2.2 Mishaps and defects in the welding process

3. Methodology

3.1 Sample collection

3.2 Sample run

3.2.1 Gamma Radiography experiment

3.2.2 Film Processing

4. Results and Discussions

5. Conclusion

Declarations

References

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