seam welded tube & pipe

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John Shingledecker, Ph.D.Sr. Technical Executive

Gen 3 CSP Summit 2021August 25, 2021 (Virtual)

Seam Welded Tube & PipeTrack A: High-Temperature Nickel-Based Alloys

Projects:DE-EE0008367, DE-EE0009378

© 2021 Electric Power Research Institute, Inc. All rights reserved.w w w . e p r i . c o m2

What effects cost?

Product Form Selection§ Based on desired sizes§ Differences in product form costs are driven by:

– Processing time– Energy intensity– Overall process yield

Seamless Tube

0.25 0.5 1 2 3 4 5 0.25 0.5 1 2 3 4 50.025 0.0250.05 0.05

0.075 0.0750.1 0.1

0.15 0.150.2 0.20.3 0.30.5 0.5

0.75 0.751 1

1.25 1.25

Welded Tube Welded Tube

0.25 0.5 1 2 3 4 5 0.25 0.5 1 2 3 4 50.01 0.010.025 0.0250.05 0.050.075 0.0750.1 0.10.15 0.150.2 0.20.25 0.25

Welded + 30% Re-drawn Tube Welded + 30% Re-drawn Tube

0.25 0.5 1 2 3 4 5 0.25 0.5 1 2 3 4 50.175 0.01750.035 0.0350.053 0.0530.07 0.070.105 0.1050.14 0.140.18 0.18

Welded Pipe Welded Pipe

5 10 15 20 25 30 5 10 15 20 25 300.25 0.250.5 0.5

0.75 0.751 1

1.25 1.251.5 1.5

Seamless Pipe Seamless Pipe

5 10 15 20 25 30 5 10 15 20 25 300.5 0.51 12 23 34 4

Red: Sizes not possible or unlikely to be possible with current processes for these alloys

Green: Possible tube size

Outer Diameter (in) Outer Diameter (in)

Wal

l Thi

ckne

ss

(in)

Wal

l Thi

ckne

ss

(in)

Yellow: Sizes requiring addition research for cost estimation purposes or possible but not demonstrated for similar alloys

Wal

l Thi

ckne

ss (i

n)

Wal

l Thi

ckne

ss (i

n)


Wal

l Thi

ckne

ss

(in)

Wal

l Thi

ckne

ss

(in)


Wal

l Thi

ckne

ss (i

n)

Wal

l Thi

ckne

ss (i

n)


N06230 740H


Wal

l Thi

ckne

ss (i

n)

Wal

l Thi

ckne

ss (i

n)

40

60

80

100

300

500

550 600 650 700 750 800

1100 1200 1300 1400

6

8

10

30

50

70

Stre

ss (M

Pa)

Average Temperature for Rupture in 100,000 hours (oC)

9-12Cr Creep-Strength Enhanced Ferritic Steels (Gr. 91, 92, 122)

Nickel-BasedAlloys

Std. 617CCA617

Inconel 740

Haynes 230

Advanced Austenitic Alloys (Super 304H, 347HFG, NF709, etc.)

Haynes 282

Average Temperature for Rupture in 100,000 hours (oF)

Stre

ss (k

si)

Materials Selection§ Higher tensile and creep strength = higher allowable

stresses§ Higher allowable stresses decrease wall thickness = reduced

cost/lb & improved cyclic capability§ *Note: alloy composition has a significant effect on cost (but

for this study, the nickel-based alloys all have similar cost)


Putting it together: Techno-Economics

Tubing scenarios

1. Gen 2 CSP Baseline: 1200F, 2” OD2. Gen 3 Molten Salt Baseline: Conceptual design in ANL 20/03 – 1391F, 1.575 OD

3. Gen 3 Molten Salt Alternative: Scenario 1 scaled to Gen 3: 1350F, 2” OD

4. Gen 3 Gas Pathway Receiver: Current design of 1346F, 0.375” OD5. Gen 3 Generic 1” tube: Intermediate between Scenario 3 and 4: 1400F, 1” OD

6. Generic Heavy-wall tubing for sCO2: 1305F at high pressure and 3” ODPiping Scenarios

1. Gen 3 Gas Pathway Piping: 1346F, 28.2” OD

2. Gen 3 Gas Pathway Multi-Pipe Estimate: Modified Scenario 1: 1346F, 9” OD3. Gen 3 Headers: 1300F, 12” OD (lower stress application)

4. sCO2 Piping: higher stress for Scenario 3: 1300F, 14” OD

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 2 3 4 5 6

740H

Cos

t/ft

Ratio

to S

eam

less

N0

6230

Tubing Scenario

SeamlessWeldedWelded+ Redrawn20% Reduction40% Reduction

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 2 3 4 5 6

740H

Cos

t/ft

Ratio

to W

elde

d N0

6230

Tubing Scenario

SeamlessWeldedWelded+ Redrawn20% Reduction40% Reduction

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1 2 3 4

740H

Cos

t/ft

Ratio

to S

eam

less

N0

6230

Piping Scenario

SeamlessWelded (0.70 WSRF)Welded (0.95 WSRF this work)20% Reduction40% Reduction

Techno-economic study§ Baseline N06230§ 10 typical/anticipated Gen 2/3 product forms§ 740H reduces cost by >20% § 740H welded products can reduce costs by

>40%– For very small diameters and thin tubes, welded

production is the only cost-effective route


Project Activities: Inconel® Alloy 740H®High-Temperature Testing & Analysis§ Relevant testing product forms (welded structures)§ New testing capabilities (multiaxial)

Manufacturing Development§ Supply chain engagement

Plate Welded Tube

Re-drawn tube

Coil

Seam-welded pipeInduction Bending

Low Cycle Fatigue of Tubes

Segment for creep testing at SIA Lab

Creep samples for EPRI Lab

Sample blank locations for tensile and fatigue

Ring Segment reserved for NDE

0-22”

22-44”

44-48”

Weld

Pressurized creep testingCross-weld creep

Post-test characterization


Successful Welded Tube Production: Inconel® Alloy 740H®

§ Two successful trials:– Passed flattening tests– Passed NDE (eddy current)

§ Yield and Tensile Strength – After aging, all tubes met ASME minimum

criteria§ Tensile Ductility (Elongation)

– All materials exceed ASME Min Requirement

§ Pressurized room temperature burst test à failures outside of weld

§ Demonstrated re-drawn tube (2” tube re-drawn to 1” – met tensile requirements)

Coil Weight kg (lbs) Coil Thickness mm(in) Coil Width mm(in) Produced Tube Diameter mm(in)

ASTM Grain Size

Trial 1 112 (247) 1.65 (0.065) 76.7 (3.02) 25.4 (1) 7.5Trial 2 230 (508) 1.65 (0.065) 157 (6.19) 50.8 (2) 7.5

For more information see: J. Shingledecker, et al. “Materials Improvements for Improved Economy of High-Temperature Components in Future Gen 3 CSP Systems.” Proceedings to SolarPACES2018. October 2-5, 2018. Casablanca, Morocco. AIP Conference Proceedings

2126, 020004 (2019); https://doi.org/10.1063/1.5117512Weld Seam

https://doi.org/10.1063/1.5117512


Successful Fabrication Activities with Welded Tubes

Autogenous welding (EPRI/SMC) – 1 to 2”

Diameter welded and redrawn tubing

Tube Bending (courtesy of TebunusTube Bending/John

Cockerill) – 2” Diameter Welded

Tubing

Solar Receiver Test Article (Courtesy of Brayton Energy) – 3/8” Diameter Welded+Redrawn

740H

1

2

3

4

5


High-Temperature Performance of Welded Tubes§ Pressurized creep test program to

evaluate long-term performance of welded tubes and develop stress allowables– Longest test durations >4,000 hrs– 740H shows a strength debit with failures

at weld seam– 740H Re-drawn tube performance

approaching base metal strength – N06230 welded tube also shows a

strength reduction § Note: greater than is currently

approved with ASME’s standard tube efficiency factor

§ Currently engaging ASME with plans to incorporate this information into the code with new stress allowables in 2022

10

100

1000

20000 22000 24000 26000 28000

Stre

ss (M

Pa)

LMP (C=19.392)

Welded 1"Welded 2"Welded - OngoingWelded+Redrawn 1"Welded_Redrawn - OngoingSeamless TubeN06230 Welded


Welded Pipe: World’s First 740H Seam-Welded Pipe§ Start with 48 in x 240 in x

0.75 in annealed plate§ Form 14 in OD Pipe§ GTA weld (740H filler, 8

passes)§ Solution anneal (1107°C)§ Radiography showed

acceptable level of porosity, no cracks or LOF

§ UST per ASTM E 213 showed no rejectable indications

20 ft long welded pipe (Swepco)

0.75” (19mm)

Pipe segment received by EPRI

0 5 10 15 20 25 30 35 40 450

5

10

15

20

X-Distance (mm)Y-

Dis

tanc

e (m

m)

17

3

10.5

0 5 10 15 20 25 30 35 40 45320

340

360

380

400

Har

dnes

s (H

V)

Cap Center Root


High-Temperature Performance of Seam-Welded Pipe

§ Standard and large sample testing has now exceeded 10,000 hours§ Short-term tests also conducted on base metal and cross-welds from the induction

pipe bend§ WSRFs >0.90 for all test and appear to be trending towards unity at long-times (open

symbols are samples in-test)

Segment for creep testing at SIA Lab

Creep samples for EPRI Lab

Sample blank locations for tensile and fatigue

Ring Segment reserved for NDE

0-22”

22-44”

44-48”

Weld

HAZ/FL – 100X Weld Metal – 100x


Ongoing research to enable reliability in Gen 3 CSP§ Example: GTI/Optimus STEP Program sCO2 (700C+) fired

heater– ~3% of tube-to-tube butt welds exhibited cracking

after PWHT§ Failure analysis confirmed Stress Relaxation

Cracking (SRxC) mechanism§ Methods for field NDE developed

– No cracking in tube-to-header, end plates, drains, etc.

§ New DOE Study SRxC (EPRI, Lehigh, Special Metals)– Assess root cause from examples of 740H cracking– Gleeble studies to evaluate fabrication variables– Transfer learnings into a specification document

First large-scale application of 740H welding (>1,600 welds) including a range of weld

geometries and thicknesses

Denuded Zones Axial Cracks near ID fusion line in Pipe Transition

R13, W4, #4

Intergranular, initiation at weld toe

Image to the rightID

ODIsolated cavities ahead of crack tip

R13, W4, #4


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seam welded tube & pipe

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