Remaining Life Assessment of an External Pressure Vessel in Creep Range and Inspection Findings

2017 ◽  
Author(s):  
Yoichi Ishizaki ◽  
Futoshi Yonekawa ◽  
Takeaki Yumoto ◽  
Teppei Suzuki ◽  
Shuji Hijikawa
Keyword(s):  
Pressure Vessel ◽  
Creep Damage ◽  
External Pressure ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Remaining Life ◽  
Assessment Technique ◽  
Creep Cavity ◽  
Creep Analysis ◽  
Remaining Life Assessment

As widely recognized in the industry, it is important to evaluate the creep damage of an elevated temperature vessel so that the mechanical integrity of the vessel can be achieved through the adequate repair and replacement planning. This is quite straight forward procedure for internal pressure vessels. For an external pressure vessel, it is not easy to assess the creep damage due to the complexity of the creep buckling analysis. Eventually, creep cavity evaluation technique without identifying the correct stress distribution has been used so often. However, due to the uncertainty of the technique itself plus conservative mindset of the inspectors, it tends to leads to an excessive maintenance most of the cases. In order to conduct a reasonable remaining life assessment, it is desirable to use the creep cavity inspection in conjunction with another assessment technique such as FEM creep analysis as stated in API 579-1/ASME FFS-1 10.5.7. In this paper, comprehensive approach with FEM and field inspection such as creep cavity evaluation to reinforce the uncertainty of each method will be demonstrated.

Fitness for Service and Remaining Life Assessment for 1-1/4Cr-1/2Mo Reactor System Piping on a Catalytic Reformer Unit

2006 ◽  
Author(s):  
Ayman M. Cheta ◽  
Ray Konet ◽  
F. Skip Hoyt
Keyword(s):  
Creep Damage ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Life Assessment ◽  
Low Alloy Steels ◽  
General Corrosion ◽  
Remaining Life ◽  
Reheat Cracking ◽  
Remaining Life Assessment ◽  
Welded Pipe

Fitness for service and remaining life assessment were performed on high temperature reactor piping to verify mechanical integrity for a desired remaining life. The NPS 20 1-1/4Cr-1/2Mo piping, which is the subject of this paper, was built in 1968 to the 1966 edition of ASA B31.3 for design conditions 465 psi at 950 °F / 365 psi at 1000 °F (3.16 MPa at 510 °C / 2.48 MPa at 538 °C) for hydrogen and naphtha service. The actual operating conditions are 400 psi at 900 °F / 330 psi at 950 °F (2.72 MPa at 482 °C / 2.24 MPa at 510 °C). Due to numerous reported failures in the industry in the 1980’s, the ASME codes for piping and pressure vessels lowered the allowable stresses for low alloy steels operating in the creep range, mainly above 900 °F (482 °C). Piping systems designed prior to changing the allowable stress do not satisfy today’s codes. The operating stresses which can lead to failure from potential damage mechanisms, e.g. creep, reheat cracking and general corrosion, are defined and their impact on fitness-for-service and remaining life evaluated. Acceptance criteria for different types of defects were established prior to the unit maintenance turnaround by: 1. Finite element modeling of assumed different degrees of weld peaking and pipe out-of-roundness for longitudinally welded pipe. 2. Piping flexibility / stress analysis to identify areas with the highest operating stresses. 3. Stresses from 1 and 2 above were used to calculate the creep life based on Larson-Miller parameter (API 530). Acceptable flaw sizes were limited by the desired remaining life. Inspection plans were developed to inspect for reheat cracking, creep damage, peaking, out of roundness, as well as general corrosion.

Crude Furnace Floor Creep Assessment and Remaining Life Assessment due to Hot Spots

2020 ◽  
Author(s):  
Gary Lee ◽  
Emerson Galacio ◽  
Romy Junio ◽  
Alex Magtibay ◽  
Elijah Griffiths ◽  
...  
Keyword(s):  
Hot Spots ◽  
Creep Damage ◽  
Life Assessment ◽  
Bottom Plate ◽  
Loading Conditions ◽  
Remaining Life ◽  
Firm Scope ◽  
Viscoelastic Analysis ◽  
Furnace Floor ◽  
Remaining Life Assessment

Abstract Fitness for Service (FFS) assessment and remaining life assessment of the furnace floor plates in a crude charge heater where hot spots up to 500°C have been observed during operation in 2018 was undertaken as a pre assessment prior to the unit turnaround. The remaining life assessment results would provide the turnaround team with firm scope for repair in order to resintate the bottom plate and avoid discovery scope. Two Finite Element (FE) models were created to account for hotspot temperature conditions measured at November 2018 and June 2019. Each of these FE models involved successive loading conditions, so that the effects of each loading scenario could be investigated. The loading conditions were applied in steps, in the following order: 1. Gravity. 2. Temperature, modelling hotspot behaviour. 3. Creep, viscoelastic analysis. Utilising the FE models created for the two hotspot conditions, remaining life was calculated and suggested that the worst location for creep damage is near burner 2 (the maximum creep damage location of the November 2018 condition). Based on the assessment, the following recommendations are made: 1. Continue to observe and maintain temperatures below the creep temperature range (i.e. no additional hotspots are created and temperatures are not increasing). 2. Undertake creep testing from metal samples. 3. Re-inspect in 8 years at the same locations where metallographic replication was performed in September 2019.

Remaining Creep Life Assessment of Service Superheat Tube Boiler

2015 ◽  
Vol 659 ◽  
pp. 686-690 ◽  
Author(s):  
Pornsak Thasanaraphan ◽  
Pannawat Thapnuy ◽  
Duangporn Ounpanich ◽  
Pratip Vongbandit
Keyword(s):  
Accumulation Rate ◽  
Creep Damage ◽  
Damage Mechanism ◽  
Thickness Measurement ◽  
Life Assessment ◽  
Remaining Life ◽  
Design Data ◽  
Remaining Life Assessment ◽  
Maintenance And Inspection ◽  
Creep Life Assessment

The demand of remaining life assessment of the boilers arises from technical, economic, and legal reasons. Creep is major damage mechanism of primary superheat tube boiler during prolong operation at high temperature and pressure in a water tube boiler. This paper presents the calculation method for the remaining life assessment due to creep damage. The service-exposed primary superheat tube made of 2.25Cr-1Mo steels. During scheduled inspection, wall thickness measurement, metallographic investigation by replica technique, design data and operating condition were used to estimate the remaining life in the form of creep damage accumulation rate calculated from life fraction using Larson-Miller Parameter. The results indicate that the primary superheat tubes satisfy in extension service life. By attaining an accurate and timely discussion of the results, the engineer can manage the maintenance and inspection schedule for the critical part in the boiler.

A Remaining Life Assessment of Autofrettaged Tubes From an LDPE Facility

2014 ◽  
Author(s):  
Jeffrey D. Cochran ◽  
Charles H. Panzarella
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Brittle Fracture ◽  
Creep Damage ◽  
Limit Load ◽  
Life Assessment ◽  
Creep Model ◽  
Normal Operation ◽  
Remaining Life ◽  
Remaining Life Assessment

The manufacture of low density polyethylene by radical polymerization regularly subjects components to extreme pressures exceeding 20 ksi and, possibly, to runaway reactions with fluid temperatures exceeding 2000 °F and pressures above 30 ksi. Components are often treated with autofrettage to induce a beneficial residual stress distribution that retards crack growth and increases fatigue life. This paper presents a case-study remaining life assessment of two autofrettaged tubes in accordance with API 579-1/ASME FFS-1. Measurements of the remaining residual stress after 40+ years in service agree with FEA predictions of the initial residual stress, indicating no significant stress relaxation over this time. Nevertheless, the MPC Omega creep model is calibrated to the tube material and used to estimate the potential for stress-relaxation due to creep. The model correctly predicts no stress relaxation for over 40 years of normal operation, but creep damage and stress relaxation are predicted for temperature excursions as low as 900 °F for 10.8 s. ASME FFS-1 procedures for assessing brittle fracture, fatigue, plastic collapse, and creep damage are then adapted for autofrettaged components. It is found that autofrettage increases resistance to brittle fracture and fatigue, does not affect limit load analyses, and alters creep damage distributions.

scholarly journals REMAINING LIFE ASSESSMENT DAN KASUS LAJU KOROSI PADA LPG STORAGE TANK KAPASITAS 50 TON

2020 ◽  
Vol 1 (2) ◽  
pp. 96-106
Author(s):  
Amam Fachrur Rozie
Keyword(s):  
Pressure Vessel ◽  
Storage Tank ◽  
Life Assessment ◽  
Remaining Life ◽  
Non Destructive Testing ◽  
Visual Examination ◽  
Destructive Testing ◽  
Working Pressure ◽  
Remaining Life Assessment ◽  
Non Destructive

LPG Storage Tank berkapasitas 50 Ton yang telah terinstalasi dan beroperasi sejak tahun 2010 akan dikaji kelayakan dan sisa umur pakai dari pressure vessel tersebut. Metode pengujian yang dipergunakan adalah Non-Destructive Testing (NDT) - Ultrasonic Testing (UT) pada bagian shell dan head untuk mendapatkan nilai actual thickness dari pressure vessel serta dilakukan Visual Examination. Nilai thickness tersebut dipergunakan untuk menganalisis dan mengkalkulasi thickness required (Treq), nilai Corrosion Rate (CR), Maximum Allowable Working Pressure (MAWP) serta umur sisa (Remaining Life) dari LPG Storage Tank tersebut. Dari hasil analisa serta perhitungan maka didapat umur sisa pakai dari LPG Storage Tank kapasitas 50 Ton adalah 18 tahun dengan nilai laju korosi sebesar 0,043 mm/thn

Structural Response and Remaining Life of Damaged Composites

2015 ◽  
Vol 813-814 ◽  
pp. 106-110
Author(s):  
Dalbir Singh ◽  
C. Ganesan ◽  
A. Rajaraman
Keyword(s):  
Hybrid Approach ◽  
Experimental Studies ◽  
Structural Response ◽  
Material Behavior ◽  
Experimental Results ◽  
Life Assessment ◽  
Nonlinear Material ◽  
Remaining Life ◽  
Design Effectiveness ◽  
Remaining Life Assessment

Composites are being used in variety of applications ranging from defense and aircraft structures, where usage is profuse, to vehicle structures and even for repair and rehabilitation. Most of these composites are made of different laminates glued together with matrix for binding and now-a-days fibers of different types are embedded in a composite matrix. The characterizations of material properties of composites are mostly experimental with analytical modeling used to simulate the system behavior. But many times, the composites develop damage or distress in the form of cracking while they are in service and this adds a different dimension as one has to evaluate the response with the damage so that its performance during its remaining life is satisfactory. This is the objective of the present study where a hybrid approach using experimental results on damaged specimens and then analytical finite element are used to evaluate response. This will considerably help in remaining life assessment-RLA- for composites with damage so that design effectiveness with damage could be assessed. This investigation has been carried out on a typical composite with carbon fiber reinforcements, manufactured by IPCL Baroda (India) with trade name INDCARF-30. Experimental studies were conducted on undamaged and damaged specimens to simulate normal continuous loading and discontinuous loading-and-unloading states in actual systems. Based on the experimental results, material characterization inputs are taken and analytical studies were carried out using ANSYS to assess the response under linear and nonlinear material behavior to find the stiffness decay. Using stiffness decay RLA was computed and curves are given to bring the influence of type of damage and load at which damage had occurred.

scholarly journals The thermal history and stress state of a fresh steam-pipeline influencing its remaining service life

2011 ◽  
Vol 15 (3) ◽  
pp. 691-704 ◽  
Author(s):  
Gordana Bakic ◽  
Vera Sijacki-Zeravcic ◽  
Milos Djukic ◽  
Stevan Maksimovic ◽  
Dusan Plesinac ◽  
...  
Keyword(s):  
Service Life ◽  
Elevated Temperatures ◽  
Operating Temperature ◽  
Life Assessment ◽  
Temperature History ◽  
Significant Variable ◽  
Remaining Life ◽  
Pipe Bend ◽  
Steam Pipeline ◽  
Remaining Life Assessment

The service life of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh- and re-heated steam, depend on the exhaustion rate of the material. Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service- and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a ?324?36 pipe bend element of a fresh steam-pipeline, made of steel class 1Cr0.3Mo0.25V, after 160 000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.

Comparative Study on Remaining Life Assessment of a Pressure Vessel, Working in Severe Conditions, Based on Results of Metallographic Replicas and Creep Tests

2021 ◽  
Vol 1164 ◽  
pp. 67-75
Author(s):  
Iuliana Duma ◽  
Alin Constantin Murariu ◽  
Aurel Valentin Bîrdeanu ◽  
Radu Nicolae Popescu
Keyword(s):  
Stainless Steel ◽  
Life Assessment ◽  
Petrochemical Plant ◽  
Remaining Life ◽  
Creep Tests ◽  
Experimental Creep ◽  
Asme Code ◽  
Remaining Life Assessment ◽  
Service Duration ◽  
Made In

The paper presents and compares the results on the reliability and remaining life assessment of a reactor (coxing box) from a petrochemical plant. The reactor shell is made of 16Mo5 (W1.5423) steel, with a thickness of 25 mm, plated with 3 mm thick X6CrAl13 (W1.4002) stainless steel. The assessment was made in two steps. For preliminary remnant life assessment, specifications of section VII of the ASME code was used followed by iRiS‑Thermo expert system. Further, experimental creep and metallographic replica analysis were performed. Results comparison of the two methods applied revealed a reduction of the preliminary estimated remaining live obtained using metallographic replica analysis. Based on the results obtained, the possibility to extend the service duration of the coxing box in the safety condition, using current process parameters, with of 20.000 hours was highlighted.

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