Design and Fabrication of Titanium Piping for Pressure ... · Titanium Grade 2/2H vs. Titanium...

Design and Fabrication of

Titanium Piping for Pressure Hydrometallurgy Service

T. Caruana, J. Clappison and L. Nightingale Mercer

Hatch Ltd.

Oakville, Ontario, Canada

L. Banfi

Loterios, Italy

Focus

Titanium Grade 2/2H vs. Titanium Grade 12

ABSTRACT

The objective of this paper is to identify the different applications of Titanium Grade

2/2H and Titanium Grade 12 piping for Pressure Hydrometallurgical Service. The

rationale behind choosing either grade will be explained throughout the paper.

Discussed in detail will be the advantages of each grade with respect to commodity

pricing, fabrication considerations (such as welding and bending), temperature and

pressure considerations, and applicable services. The results of this paper will aid in the

creation of guidelines to optimize titanium piping systems.

INTRODUCTION/BACKGROUND

The focus of this paper is to determine the optimum grade of titanium piping for

Autoclave technology circuits. The function of an Autoclave circuit is a chemical process

operating under elevated pressures and temperatures. The primary pressure vessels in

these circuits are the Heater vessel (for Heat Recovery), the Autoclave (primary reactor)

and the Flash Vessel (Pressure let down). The piping systems connect these vessels to

complete the circuit. An array of material is used for the various services in the

autoclave circuits. Materials are selected depending on the fluid service, erosion and

corrosion rates and temperature and pressure requirements.

Titanium is used in both gold pressure oxidation (POX) and Nickel high pressure acid

leach (HPAL) autoclave circuits for its corrosion resistance to sulfuric acid at elevated

temperatures. Levels of sulfuric acid (H2SO4) vary from 0% to 10% w/w and

temperatures range from 215°C (419°F) to 260°C (500°F) for these autoclave circuits.

Common grades of titanium used for pressure piping in these applications are grade 2

and 12. However with the addition of the Grade 2H to the ASME code in 2009, it will be

utilized for this application in lieu of Grade 2.

Titanium is used for slurry feed lines, high pressure vent lines, autoclave discharge lines

and safety relief lines that are typically rated for a pressure class of 300# or higher. Low

pressure applications are flash vessel vent lines, flash vessel slurry discharge lines and

slurry sampling lines which are typically rated for a pressure class of 150#. Refer to

Figure 1 for a simplified autoclave circuit flow diagram.

Figure 1 – Simplified Autoclave Circuit Flow Diagram

The paper will discuss the different aspects to be considered when selecting the grade

of titanium for the piping system with a focus on piping systems with a pressure class of

300 and greater. These aspects include material properties, corrosion resistance, code

requirements, fabrication limitations and economical considerations. Three case studies

will be discussed throughout the paper to highlight the differences between the grades

of titanium.

Material Properties

Titanium is available in several different grades to suit many applications. Table 1 is a

generalized table to illustrate some of the mechanical and chemical properties of the

grades of Titanium we will be discussing throughout this paper.

Table 1 – Titanium Properties

Titanium Nominal Composition Min. Tensile Strength

Required MPa (ksi)(1)

Grade 2 Commercially Pure +99% pure

Titanium 345 (50)

Grade 2H Commercially Pure +99% pure

Titanium 400 (58)

Grade 12 Alloyed

Balance titanium

0.3% molybdenum

0.8% nickel

485 (70)

The production and composition of Titanium Grade 2 is identical to Titanium Grade 2H.

However, Grade 2H must have a minimum Ultimate Tensile Strength of 58ksi. The H

grades were added in response to a user association request based on its study of over

5200 commercial Grade 2, 7, 16 and 26 test reports, where over 99% met the 400 MPa

(58 ksi) minimum UTS (ASME 2007 Section II, Part B, Specification For Titanium and

Titanium Alloy Strip, Sheet, and Plate). This has resulted in an increase of tensile strength

by 16%.

Titanium is well known for its excellent corrosion resistance and superior strength-to-

weight ratio. However, the addition of alloys to Grade 12 improves the tensile strength

and creep resistance of Grade 12 over Grade 2/2H Titanium. Grade 2/2H is limited in

hydrometallurgical services with higher temperatures. At elevated temperatures pure

titanium becomes soft, therefore requiring the need for alloying. Nickel and

Molybdenum are the main elements added to Titanium Grade 12 to improve its

performance at these temperatures. Nickel is added to increase strength and

toughness. Molybdenum is added to help resist softening at higher temperatures and

assures high creep strength allowing Grade 12 to be used in higher temperature

services.

Titanium alloys Gr 2/2H and Gr 12 are resistant to only dilute solutions of

uncontaminated sulphuric acid. At room temperature Gr 2/2H is only resistant to 5%

w/w acid, while Gr 12 is resistant to 10% w/w acid. In comparison, stainless steel 316L is

resistant to 20% w/w acid. However, the presence multi-valent metal ions such as cupric

and ferric inhibit the corrosion of Gr 2/2H and Gr 12 in sulphuric acid. The addition of

16 grams per liter of ferric ion allows Gr 2/2H to resist 20% w/w acid up to the boiling

point. Most hydrometallurgical solutions contain ferric ion which allows the application

of these titanium alloys(2).

Typically, both Grade 2/2H and Grade 12 Titanium are suitable for various applications

of most pressure oxidation (POX) and high pressure acid leach (HPAL) autoclave circuits.

However, every process requires corrosion testing to assess the suitability of the

material of construction, for specific conditions and solution composition.

Pipe Material Specification and Design Rating

Pressure Class and wall thickness are two primary factors that must be determined to

establish the specification of a piping system. The design pressure and temperature are

dictated by the autoclave circuit design conditions. These values along with the selected

material properties, establish the pressure class and wall thickness.

The pressure class (i.e. flange class) is determined by the design pressure and

temperature requirement and the material properties. ASME B16.5, Pipe Flanges and

Flanged Fittings(3) list pressure/temperature and pressure rating for the standard

pressure class for various material. However, Titanium is not a listed material in this

standard. Therefore, the pressure class has been determined by using ASME B16.5, 2010,

Appendix A equations(3). These pressure class temperature/pressure ratings are

important as they are the design condition for the valves that are specified and design

to ASME B16.34 Valves – Flanged, Threaded, and Welding End(4).

Figure 2 illustrates the pressure and temperature ratings by pressure class 150, 300, 600

and 900 for Titanium grade 2, 2H and 12. Please note that Titanium Grade 2 is strictly

shown to illustrate the 16% difference in minimum tensile strength. Due to the

differences in the allowable stress of the different grades of titanium, it is possible to

have a different pressure class for the same design conditions of the piping system.

Class 150 does not have a significant difference in the pressure rating of all 3 grades.

However, pressure rating for class 300 and higher differ significantly. All material

properties have been taken from ASME 2010 Boiler Pressure Vessel Code, Section II, Part

D(3).

Pressure/Temperature Ratings (Ti 2, 2H &12)

0.0

2000.0

4000.0

6000.0

8000.0

10000.0

12000.0

14000.0

16000.0

0 50 100 150 200 250 300 350

Temp C

Pre

ssu

re k

Pa

Class 150 Gr. 2H

Class 300 Gr. 2H

Class 600 Gr. 2H

Class 900 Gr. 2H

Class 150 Gr. 2

Class 300 Gr. 2

Class 600 Gr. 2

Class 900 Gr. 2

Class 150 Gr. 12

Class 300 Gr. 12

Class 600 Gr. 12

Class 900 Gr. 12

POX

HPAL

Figure 2 – Titanium Pressure Temperature Class Ratings and Autoclave Design Conditions

To focus on the design conditions for autoclave applications, the design conditions for

several POX gold and HPAL nickel laterite autoclaves have been included in Figure 1

above. There are two different cases for the POX autoclave. The first case illustrates that

the pressure class can be either class 600 for Titanium Grade 2H or class 300 for

Titanium Grade 12. The second case illustrates the pressure class 600 for both Titanium

Grade 2H and Titanium Grade 12. For the HPAL autoclave in case three, the pressure

class can be either 900 for Titanium Grade 2H or 600 for Titanium Grade 12. These will

be the areas of focus for the three case studies throughout the paper. Design

conditions for the three case studies are summarized in Table 2.

Table 2 – Case Study Design Conditions

Case Study 1

POX

Case Study 2

POX

Case Study 3

HPAL

Material Ti

Grade 2H

Ti

Grade 12

Ti

Grade 2H

Ti

Grade 12

Ti

Grade 2H

Ti

Grade 12

Flange Rating 600# 300# 600# 600# 900# 600#

Corrosion Allowance mm (inch) 3 (0.1) 3 (0.1) 3 (0.1)

Design Temperature °C (°F) 230 (446) 249 (480) 260 (500)

Design Pressure kPa(g) (psig) 3392 (491) 3875 (562) 5000 (725)

The pressure class is important as it will dictate the pressure class of the valves that are a

significant part of the cost for these types of piping systems. For safe isolation, the

majority of these piping systems have a double block and bleed valve arrangement. For

the case studies mentioned throughout this paper, the valve costs contribute to 70%-

85% of the entire piping system cost. Therefore the valves are key components that

impact the total cost of a titanium piping system.

Typically the flanges in titanium piping are specified as ASTM A-105 carbon steel lap

joint flanges with titanium stub ends to minimize cost. However, the pressure rating of

the piping system is still governed by the titanium pressure class as the flange valve

bodies are forged titanium and titanium has a lower pressure/temperature rating than

carbon steel. The carbon steel lap joint flanges are selected to match the pressure class

of the valve.

The flange rating for titanium may not be the limiting case of the specification as it is

with other piping material specifications such as carbon steel or stainless steel. To

minimize cost, the wall thickness is calculated based on the actual required design

pressure and temperature of the system and not the flange rating. This is typical of

titanium piping specifications such as the case studies presented, as pressure class

rating would result in a much thicker wall that is not required for the application and in

consequence result in a greater cost.

Pipe Wall Thickness

Wall thicknesses have been determined in accordance with ASME B31.3, Process

Piping(6) Code. The following have been considered in the calculation:

3 mm (0.1 inch) corrosion allowance.

Fabrication tolerances per ASTM SB-862 Titanium and Titanium Alloy Welded Pipe

for available pipe schedule.

No under tolerance for engineered wall pipe.

Quality factor of 0.85 for welded pipe. (No additional NDE has been considered).

Quality factor of 1.00 for seamless pipe. (Applies only to schedule 160 2” pipe).

Where practical the next closest wall schedule has been selected and where the wall

schedule would result in overdesign the next available standard plate thickness has been

selected to meet the code requirements. The following tables summarize the wall

thickness for the three case studies. Wall Schedule is per ASME B36.10M, 2004(7).

Table 3A - POX Gold Discharge Line Wall Thickness Comparison

Case Study 1 POX

Pipe

Diameter

mm (inch)

Class 600 Grade 2H

Schedule

Wall

Thickness

mm (inch)

Class 300 Grade 12

Schedule

Wall

Thickness

mm (inch)

50 (2) 80 5.54 (0.218) 80 5.54 (0.218)

100 (4) 80 8.56 (0.337) 80 8.56 (0.337)

150 (6) ENG. WALL 3/8" plate 9.525 (0.375) ENG. WALL 3/8" plate 9.525 (0.375)




Table 3B - POX Gold Discharge Line Wall Thickness Comparison

Case Study 2 POX

Pipe

Diameter

mm (inch)

Class 600 Grade 2H

Schedule

Wall

Thickness

mm (inch)

Class 600 Grade 12

Schedule

Wall

Thickness

mm (inch)

50 (2) 80 5.54 (0.218) 80 5.54 (0.218)

100 (4) 80 8.56 (0.337) 80 8.56 (0.337)





Table 3C - HPAL Nickel Laterite Discharge Line Wall Thickness Comparison

Case Study 3 HPAL

Pipe

Diameter

mm (inch)

Class 900 Grade 2H

Schedule

Wall

Thickness

mm (inch)

Class 600 Grade 12

Schedule

Wall

Thickness

mm (inch)

50 (2) 160 8.74 (0.344) 160 8.74 (0.344)

100 (4) ENG. WALL 3/8" plate 9.525 (0.375) 80 8.56 (0.337)





For case study 1, Table 3A, the wall thickness for both grade 2H and grade 12 are the

same for all sizes except for size DN 250 (NPS 10”) where Grade 12 is thinner than Grade

2H. In case study 2, the wall thickness for size DN 200 (NPS 8”) and DN 300 (NPS 12”)

for Grade 12 are less than the Grade 2H wall. For case study 3, Table 3C, Grade 12 has a

thinner wall for sizes between DN 100 and DN 300. The cost impact resulting in the

different wall thickness will be reflected in the cost analysis.

Fabrication Considerations

There are a few fabrication requirements that need to be considered before selecting

the most suitable material. The different material properties of the two grades of

titanium result in different requirements during fabrication and also have different

fabrication limitations.

For welded titanium pipe both grades are formed from plate and seam welded. Titanium

grade 2/2H is “as welded” from plate and does not require any further processing unlike

Titanium grade 12. Titanium Grade 12 requires solution annealing of the seam to

remove residual stresses and to produce a uniform normalized grain. Furthermore,

Grade 12 requires a pickling process after the heat treatment to restore surface finish.

These additional processes result in reduced production rate and increased lead time for

delivery.

Although virtually any combination of size and schedule of pipe can be formed from

titanium plate, difficulties arise when dealing with small bore piping (2” and smaller)

with a wall thickness of schedule 160 or greater. An alternative to this problem is

selecting seamless piping or tubing when faced with this situation. However, in general,

seamless piping results in a higher cost as opposed to welded piping.

Titanium grade 12 exhibits more limitations than Grade 2/2H for bending and forming.

Titanium grade 2/2H can be formed using a cold bending process at thicknesses up to

50 mm where titanium grade 12, bending can only be performed at thicknesses up to 38

mm.

Table 4A and 4B list the maximum wall thickness that can be made into a 3D bends for

both welded and seamless pipe. The minimum wall thickness for 3D bends should

generally be no less than 3 mm. This is typical for hot bending. In most cases, the

starting wall thickness for the bend will be that of the pipe in which it will be welded to

however wall thinning must be considered.

Table 4A – Maximum Wall Thickness for Welded 3D Bends

Max Thickness for 3D bend – Welded Pipe

Pipe

Diameter

mm (inch)

Ti

Grade 2/2H

Ti

Grade 12

50 (2) sch 80 sch 40

100 (4) -300 (12) sch 120 sch 80

Table 4B – Maximum Wall Thickness for Seamless 3D Bends

Max Thickness for 3D bend - Seamless Pipe

Pipe

Diameter

mm (inch)

Ti

Grade 2/2H

Ti

Grade 12

50 (2) -300 (12) sch 160 sch 160

Cost Analysis

Raw material costs vary between the two different grades of titanium. Generally titanium

grade 12 is about 10-12% higher than grade 2/2H due to the presence of nickel and

different fabrication requirements. The % increase in cost of pipe and fittings trend

similar to the raw material. However, the valve cost is not greatly affected by the grade

of Titanium. The cost advantage from the valves occurs when a lower pressure class can

be used. Table 5 illustrates the percent difference for pipe, fittings and 3D bends for the

same thickness.

Table 5 – % Unit Price of Titanium Grade 12 vs. Titanium Grade 2H

Pipe Pipe 3D Bends Stub Ends Valves

Small Bore Piping

50 mm (2 inch) 124% 135% 109% 102%

Large Bore Piping

100 mm (4 inch) to

300 mm (12 inch)

115% 109% 107% 103%

An autoclave discharge line from an existing POX design is being utilized for the cost

analysis for all three case studies. All pipe and fittings found on the main run are

included in the cost analysis. All secondary lines for drains, instrumentation, flushing,

etc. are disregarded. To determine the most cost effective grade for each case study,

costs have been established for material, fabrication and valves. The cost analysis

provided for each case study provides cost for the piping system with and without the

valves. Table 6 lists all components included in the cost analysis.

Table 6 – Case Study Bill of Material

Fitting Material Specification

Length m

(ft) Quantity

Pipe ASTM B-862 26 (85) 1

3D Bend ASTM B-862 - 3

Stub End ASTM B-862 - 13

Valve

Titanium Metal Seated Ball

Valve - 2

Case Study 1

Figure 3A and 3B illustrates the cost difference between Class 600 Grade 2/2H and Class

300 Grade 12. All costs have been presented as a percentage difference of the total cost

over the total cost of Grade 12. Figure 3A includes only the cost of material and

fabrication. Figure 3B includes the cost of the valves.

For pipe sizes in the range of DN 50 (NPS 2”) to DN 300 (NPS 12”) the total cost

difference is between 10% - 20% with the exception of size DN 250 (NPS 10”) in which

Grade 2H is 5% greater (Figure 3A). This is further illustrated in Table 3A where 10 inch

piping for Grade 12 is thinner than Grade 2H. Therefore in most cases it is more

economical to select Grade 2/2H as opposed to Grade 12.

When considering the cost of the piping system with the isolation valves, the cost gap is

reduced and the difference between Grade 2H and 12 is between 0% and 15%, where all

sizes with grade 12 are consistently less than Grade 2H. The valves have a significant

cost impact to the overall cost of the piping system as shown in Figure 3B. This case

illustrates that unlike the case 1A, selecting grade 12 is more economical overall for the

case study when including isolation valves. This is the result of the lower pressure class

for Grade 12 valves

To further economize the piping system, the scenario using Grade 2 pipe with Grade 12,

Class 300 valves is also included in Figure 3B. In general, this case is the most

economical when compared to Grade 2/2H piping with class 600 valves and Grade 12

piping with Class 300 valves.

Case Study 1A POX

Class 600# Grade 2H /Class 300# Grade 12

Piping and Fabrication Only

-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)

Pipe DN, mm (NPS,inches)

% d

iffe

ren

ce o

f th

e T

ota

l C

ost

Gra

de 1

2 Grade 2H

Figure 3A - POX Discharge without Isolation Valves – Cost VS Diameter

Case Study 1B POX

Class 600 Grade 2H/Class 300 Grade 12

Pipe, Fabrication and Valves

-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)

Pipe DN, mm (NPS, inch)

% d

iffe

ren

ce o

f th

e t

oal

co

st

of

Gra

de

12

Gr 2H Pipe & Class 600 Valves

Gr 2H Pipe & Class 300 Gr 12 Valves

Figure 3B - POX Discharge with Isolation Valve – Cost VS Diameter

Case Study 2

Figure 4A and 4B summarizes the cost difference between Class 600 Grade 2H and Class

600 Grade 12. Figure 4A includes only the cost of material and fabrication. Figure 4B

includes the cost of the valves.

For smaller pipe sizes in the range of DN 50 (NPS 2”) to DN 150 (NPS 6”) the Grade 2/2H

is between 10% - 20% less then the Grade 12 costs (Figure 4A). For larger pipe sizes in

the range of DN 200 (NPS 8”) to DN 300 (12”) the cost of Grade 2/2H is between 0% and

10% greater than Grade 12. This is further illustrated in Table 3B where larger pipe for

Grade 12 is thinner than Grade 2H. Therefore it is more economical to select Grade 2H

for smaller sizes DN 150 (6”) and below where wall thickness is the same for both

grades and Grade 12 for sizes DN 200 (8”) and above where the wall thickness can vary

between the grades.


reduced and the difference between Grade 2H and 12 is between 0% and 5%, in which

Grade 2H is less than Grade 12. The valves have a significant cost impact to the overall

cost of the piping system as shown in Figure 3B. This case is similar to the case above,

however grade 2H is a more economical selection for a greater range of sizes.

To further economize the piping system, the scenario using Grade 12 pipe with Grade

2H, Class 600 valves is also included in Figure 4B. In general, this case is the most

economical for size DN 200 (NPS 8”) and larger. There is no cost advantage in the

smaller sizes. When the pipe class is the same for both grades, grade 2H valves are the

more economical choice.

Case Study 2A POX



-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)

Pipe DN, mm (NPS, inches)

% D

iffe

ren

ce o

f th

e T

ota

l C

ost

for

Gr

12

Grade 2H

Figure 4A – POX Discharge without Isolation Valve – Cost VS Diameter

Case Study 2B POX

Class 600 Gr 2H/Class 600 Gr 12


-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


% d

iffe

ren

ce o

f th

e t

ota

l co

st

of

Gr

12 Grade 2H Pipe and Valves

Grade 12 Pipe and Grade 2H Valves

Figure 4B – POX Discharge with Isolation Valve – Cost VS Diameter

Case Study 3

Figure 5A and 5B summarizes the cost difference between Class 900 Grade 2H and Class

600 Grade 12. Figure 5A includes only the cost of material and fabrication. Figure 5B

includes the cost of the valves.

The costs include material and fabrication costs only. Unlike the previous case studies,

there is a higher total cost difference of 0% - 25% where Grade 2H costs are higher for

sizes DN150 and larger, and grade 2H costs are lower for sizes DN 50 and DN 100. With

respect to wall thickness, as illustrated in Table 3C, Grade 12 has a wall thickness that is

either equal to or less than that of Grade 2H. From Figure 5A it is more economical to

select Grade 2H for smaller sizes and Grade 12 for larger sizes.


reduced and the difference between Grade 2H and 12 is between 5% and 18%, in which

Grade 12 is less than Grade 2H with the exception of DN 50 (2”). The valves have a

significant cost impact to the overall cost of the piping system as shown in Figure 5B. In

this case, Grade 12 pipe and valves is the more economical selection.

To further economize the piping system, the scenario using Grade 2H pipe with Grade

12, Class 600 valves is also included in Figure 5B. This case is the most economical for

only pipe size DN 50 (NPS 2”) and this is attributed the requirement of seamless pipe for

this size and wall thickness for both grades.

Case Study 3A HPAL



-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


% D

iffe

ren

ce o

f th

e t

ota

l C

ost

Gr

12

Grade 2H

Figure 5A – HPAL Discharge without Isolation Valve – Cost VS Diameter

Case Study 3B HPAL

Class 900 Gr 2H and Class 600 Grade 12


-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


% D

iffe

ren

ce o

f th

e t

ota

l C

ost

of

Gr

12


Gr 2H Pipe and Class 600 Gr 12 Valves

Figure 5B – HPAL Discharge with Isolation Valve – Cost VS Diameter

Summary/Conclusion

When choosing between titanium grade 2H and grade 12 for the case studies

representing POX and HPAL, fabrication limitations were not a factor in the case. All

calculated wall thicknesses for pipe and 3D bends are practical, however some pipe,

mainly DN 50 (NPS 2”) must be supplied as seamless pipe due to wall thickness.

For the 300/600 class POX applications, grade 2H is the more economical choice and

grade 12 is the better choice for the valve due to the lower pressure class.

For class 600 POX applications, Grade 12 should be considered for the larger pipe size

where thinner pipe wall can be used. Grade 2H should be selected for valves as there is

no justification for selecting the higher cost Grade 12 valves.

For HPAL applications, Grade 12 pipe and valves are generally the more economical

option for the majority of the sizes.

Grade 12 pipe and fittings should be selected over grade 2H only when a thinner wall

thickness can be used. The savings from the reduced wall thickness exceed the cost

premium for grade 12. Grade 12 valves should be selected only if a lower pressure class

can be used.

The valves in the particular circuit should always be considered as they can affect the

outcome of the cost analysis. In any case, availability and delivery of materials should

always be considered, as it could be the overriding factor.

References

(1) 2010 ASME Boiler and Pressure Vessel Code, Section 2, Part D – Properties

(Metric), Materials, The American Society of Mechanical Engineers, Three Park

Avenue, NY, USA, 2010

(2) “Corrosion Resistance of Titanium”, Titanium Metals Corporation, TIMET, Denver,

Colorado, USA

(3) ASME B16.5 – 2009 Pipe Flanges and Flanged Fittings NPS ½ Through NSP 24

Metric/Inch Standard, The American Society of Mechanical Engineers, Three Park

Avenue, NY, USA, 2009

(4) ASME B16.34 – 2009 Valves – Flanges, Threaded, and Welding End, The American

Society of Mechanical Engineers, Three Park Avenue, NY, USA, 2009

(5) 2010 ASME Boiler and Pressure Vessel Code, Section 2, Part B – Nonferrous

Material Specifications, Materials (Specification for Titanium and Titanium Alloy

Strip, Sheet, and Plate), The American Society of Mechanical Engineers, Three

Park Avenue, NY, USA, 2010

(6) ASME B31.3 - 2008 Process Piping ASME Code for Pressure Piping, B31, The

American Society of Mechanical Engineers, Three Park Avenue, NY, USA, 2008

(7) ASME B36.10M – 2004 Welded and Seamless Wrought Steel Pipe, The American

Society of Mechanical Engineers, Three Park Avenue, NY, USA, 2004

(8) ASTM B862 – 09 Standard Specification for Titanium and Titanium Alloy Welded

Pipe, American Society for Testing and Materials, West Conshohocken, PA, USA,

2009

Acknowledgements

Mogas Industries, Houston, Texas

Design and Fabrication of

Titanium Piping for

Hydrometallurgy Service

Laura Nightingale Mercer

Hatch Ltd.Tracey Caruana

Hatch Ltd.

OverviewOverv

iew

• Titanium Grade 2/2H versus Titanium Grade 12

• Fabrication Considerations

• Temperature and Pressure Considerations

• Economical Considerations

• Conclusion - Optimization of Titanium Piping Systems

The Use of Titanium Piping in

Autoclave Technology CircuitsOverv

iew

Grade 2/2H versus Grade 12:

PropertiesMate

rials

• Grade 2 and Grade 2H identical chemical composition –

2H requires UTS of 58ksi

Titanium Nominal CompositionMin. Tensile Strength Required

MPa (ksi)

Grade 2Commercially

Pure

+99% pure

Titanium345 (50)

Grade 2HCommercially

Pure

+99% pure

Titanium400 (58)

Grade 12 Alloyed

Balance

titanium 0.3%

molybdenum

0.8% nickel

485 (70)

Fabrication Considerations

Fab

ricatio

n

• Welded pipe

– both grades formed from plate and seam

welded

– maximum wall thickness

• Grade 2/2H – 50 mm

• Gr12 – 38 mm

– Titanium Gr. 12 requires annealing along

seam to remove residual stresses

• Seamless pipe required for piping 2” and

smaller with a wall thickness of Sch. 160

or greater

3D Bending – Max Wall Thickness

Max Thickness for 3D bend – Welded Pipe

Pipe

Diameter

mm (inch)

Ti

Grade 2/2H

Ti

Grade 12

50 (2) sch 80 sch 40

100 (4) -300 (12) sch 120 sch 80

Fab

ricatio

n

Max Thickness for 3D bend - Seamless Pipe

Pipe

Diameter

mm (inch)

Ti

Grade 2/2H

Ti

Grade 12

50 (2) -300 (12) sch 160 sch 160

Factors in Determining the

Specification of a Piping System

• Autoclave Design Conditions

• Material Properties

• Wall Thickness

• Pressure Class

Sp

ecific

atio

n

Wall Thickness

• Established by design conditions not flange

rating

• Calculated as per B31.3 Pressure Piping

– 3 mm corrosion allowance, fabrication

– tolerances (per ASTM B-862),

– no under-tolerance for engineered wall,

– E=0.85 for welded pipe (min NDT)

– E=1 for seamless pipe

Specificatio

n

Pressure Class

• ASME B16.5 Appendix A

• Dictates the Pressure Class of the Valves

– contributes to 70%-85% of the system cost

• Carbon Steel Lap Joint flanges normally

selected with Titanium stub ends

• Governed by Titanium Pressure Class due

to Titanium flange valve bodies

– Lower pressure/temperature rating than Carbon

Steel Flange

Specificatio

n

Pre

ssure

Cla

ss

Pressure and Temperature Ratings by

Pressure Class For TitaniumTitanium Pressure Class and Autoclave Design Conditions

Pressure/Temperature Ratings (Ti 2, 2H &12)

0.0

2000.0

4000.0

6000.0

8000.0

10000.0

12000.0

14000.0

16000.0

0 50 100 150 200 250 300 350

Temp C

Pre

ssu

re k

Pa

Class 150 Gr. 2H

Class 300 Gr. 2H

Class 600 Gr. 2H

Class 900 Gr. 2H

Class 150 Gr. 2

Class 300 Gr. 2

Class 600 Gr. 2

Class 900 Gr. 2

Class 150 Gr. 12

Class 300 Gr. 12

Class 600 Gr. 12

Class 900 Gr. 12

POX

HPAL

Case StudiesCase S

tudy

Case Study 1

POX

Case Study 2

POX

Case Study 3

HPAL

Material

Ti

Grade

2H

Ti

Grade

12

Ti

Grade

2H

Ti

Grade

12

Ti

Grade

2H

Ti

Grade

12

Flange Rating600# 300# 600# 600# 900# 600#

Corrosion Allowance

mm (inch) 3 (0.1) 3 (0.1) 3 (0.1)

Design Temperature °C

(°F) 230 (446) 249 (480) 260 (500)

Design Pressure kPa (psi) 3392 (491) 3875 (562) 5000 (725)

Autoclave Discharge LineCase

Stu

dy

Cost AnalysisCase

Stu

dy

Bill of Material

Fitting Material Specification Length m (ft) Quantity

Pipe ASTM B-862 26 (85) 1

3D Bend ASTM B-862 - 3

Stub End ASTM B-862 - 13

Valve Titanium - 2

POX – Wall Thickness Comparison

Case Study 1: Class 600 Grade 2/2H vs

Class 300 Grade 12

Case

Stu

dy

Case Study 1 POX

Pipe Dia.mm (inch)

Class 600 Grade 2HSchedule

Wall Thk.

Mm

(inch)

Class 300 Grade 12 Schedule

Wall Thk.mm (inch)

50 (2) 80 5.54 (0.218) 80 5.54 (0.218)

100 (4) 80 8.56 (0.337) 80 8.56 (0.337)





Grade 2H wall has the same thickness as Grade 12 wall

eco

no

mic

s

Piping & Fabrication

Case Study 1A POX

Class 600# Grade 2H /Class 300# Grade 12


-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)

Pipe DN, mm (NPS,inches)

% d

iffe

ren

ce o

f th

e T

ota

l C

ost

G12

Grade 2H

Grade 2H is 10% to 20% cheaper than Grade 12.

eco

no

mic

s

Piping, Fabrication & Isolation Valves

For lower class POX applications, Gr. 2H Pipe with Gr. 12,

Class 300 Valves are the more economical choice

due to a lower pressure class

Case Study 1A POX



-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


To

tal

Co

st

/To

tal

Co

st

of

Gra

de 1

2,

%


Gr 2H Valve & Class 300 Gr 12 Valves

POX – Wall Thickness Comparison


Class 600 Grade 12

Case

Stu

dy

• Small bore: Grade 12 Wall is equal to Grade 2H Wall

• Large Bore: Grade 12 Wall is less than Grade 2H Wall

Case Study 2 POX

Pipe Dia. mm (inch)

Class 600 Grade 2HSchedule / Plate

Wall Thk. mm (inch)

Class 600 Grade 12Schedule / Plate

Wall Thk. mm (inch)

50 (2) 80 5.54 (0.218) 80 5.54 (0.218)

100 (4) 80 8.56 (0.337) 80 8.56 (0.337)




300 (12) ENG. WALL 5/8" plate 15.875(0.625) ENG. WALL 1/2" plate 12.7 (0.500)

eco

no

mic

s


Small bore: Grade 2H is 10% to 20% less than Grade 12

Large Bore: Grade 12 is 0% to 15% less than Grade 2H

Case Study 2A POX



-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


% D

iffe

ren

ce o

f th

e T

ota

l C

ost

for

Gr

12

Grade 2H

eco

no

mic

s


Class 600# POX applicationsGr. 12 is more economical for larger pipe where thinner wall is used

Grade 2H valves should be used (no added value to selecting

Gr. 12)

Case Study 2B POX

Class 600 Gr 2H/Class 600 Gr 12


-40%

-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


To

tal

Co

st/

To

tal

Co

st

of

Gra

de 1

2,

%

Grade 2H Pipe and Valves

Grade 12 Pipe and Grade 2H Valves

HPAL – Wall Thickness Comparison


Class 600 Grade 12

Case

Stu

dy

• 2” seamless pipe: Grade 12 Wall is equal to Grade 2H Wall

• 4” and above: Grade 12 Wall is less than Grade 2H Wall

Case Study 3 HPAL

Pipe Diameter mm (inch)

Class 900 Grade 2H Schedule

Wall

Thickness

mm (inch)

Class 600 Grade 12 Schedule

Wall

Thickness

mm (inch)

50 (2) 160 8.74 (0.344) 160 8.74 (0.344)

100 (4) ENG. WALL 3/8" plate 9.525 (0.375) 80 8.56 (0.337)



250 (10) ENG. WALL 5/8" plate 15.875(0.625) ENG. WALL 1/2" plate 12.7 (0.500)


eco

no

mic

s


Small bore: Grade 2H is 0% to 30% less than Grade 12

Large Bore: Grade 12 is 0% to 30% less than Grade 2H

Case Study 3A HPAL



-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


To

tal

Co

st/

To

tal

Co

st

for

Gra

de 1

2,

%

Grade 2H

eco

no

mic

s


HPAL applications

Grade 12 pipe and valves are more economical for most

sizes

Case Study 3B HPAL

Class 900 Gr 2H and Class 600 Grade 12


-30%

-20%

-10%

0%

10%

20%

30%

40%

50 (2) 100 (4) 150 (6) 200 (8) 250 (10) 300 (12)


To

tal

Co

st/

To

tal

Co

st

of

Gr

12,

%


Gr 2H Pipe and Class 600 Gr 12 Valves

Conclusion – Optimization of a

piping system

Co

nclu

sion

• Fabrication limitations did not play a factor in

choosing between Grade 12 and Grade 2/2H

•Smaller pipe with thicker wall must be supplied as

seamless

•Grade 12 pipe & fittings should be selected over

Grade 2H when thinner wall can be used

•Grade 12 valves to be selected if a lower pressure

class than Grade 2H can be used.

•Other factors to be considered – availability and

delivery

AUTOCLAVE

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Design and Fabrication of Titanium Piping for Pressure ... · Titanium Grade 2/2H vs. Titanium...

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