Page 1
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.
Page 2
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
Page 3
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.
Page 4
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).
Page 5
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)
Page 6
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).
Page 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)
200 (8) ENG. WALL 3/8" plate 9.525 (0.375) ENG. WALL 3/8" plate 9.525 (0.375)
250 (10) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 3/8" plate 9.525 (0.375)
300 (12) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 1/2" plate 12.7 (0.500)
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)
150 (6) ENG. WALL 3/8" plate 9.525 (0.375) ENG. WALL 3/8" plate 9.525 (0.375)
200 (8) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 3/8" plate 9.525 (0.375)
250 (10) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 1/2" plate 12.7 (0.500)
300 (12) ENG. WALL 5/8" plate 15.875 (0.625) ENG. WALL 1/2" plate 12.7 (0.500)
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)
150 (6) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 3/8" plate 9.525 (0.375)
200 (8) ENG. WALL 5/8" plate 15.875 (0.625) ENG. WALL 1/2" plate 12.7 (0.500)
250 (10) ENG. WALL 5/8" plate 15.875 (0.625) ENG. WALL 1/2" plate 12.7 (0.500)
300 (12) ENG. WALL 3/4" plate 19.05 (0.750) ENG. WALL 5/8" plate 15.875 (0.625)
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.
Page 8
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
Page 9
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
Page 10
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
Page 11
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.
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 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
Page 12
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
Class 600 Grade 2H/Class 600 Grade 12
Piping and Fabrication Only
-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
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
ota
l co
st
of
Gr
12 Grade 2H Pipe and Valves
Grade 12 Pipe and Grade 2H Valves
Page 13
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.
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 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
Class 900 Grade 2H/Class 600 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
Gr
12
Grade 2H
Figure 5A – HPAL Discharge without Isolation Valve – Cost VS Diameter
Page 14
Case Study 3B HPAL
Class 900 Gr 2H and Class 600 Grade 12
Pipe, Fabrication and Valves
-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
of
Gr
12
Gr 2H Pipe & Class 900 Valves
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.
Page 15
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.
Page 16
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)
150 (6) ENG. WALL 3/8" plate 9.525 (0.375) ENG. WALL 3/8" plate 9.525 (0.375)
200 (8) ENG. WALL 3/8" plate 9.525 (0.375) ENG. WALL 3/8" plate 9.525 (0.375)
250 (10) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 3/8" plate 9.525 (0.375)
300 (12) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 1/2" plate 12.7 (0.500)
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
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
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
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)
To
tal
Co
st
/To
tal
Co
st
of
Gra
de 1
2,
%
Gr 2H Pipe & Class 600 Valves
Gr 2H Valve & Class 300 Gr 12 Valves
POX – Wall Thickness Comparison
Case Study 2: Class 600 Grade 2/2H vs
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)
150 (6) ENG. WALL 3/8" plate 9.525 (0.375) ENG. WALL 3/8" plate 9.525 (0.375)
200 (8) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 3/8" plate 9.525 (0.375)
250 (10) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 1/2" plate 12.7 (0.500)
300 (12) ENG. WALL 5/8" plate 15.875(0.625) ENG. WALL 1/2" plate 12.7 (0.500)
eco
no
mic
s
Piping & Fabrication
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
Class 600 Grade 2H/Class 600 Grade 12
Piping and Fabrication Only
-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
eco
no
mic
s
Piping, Fabrication & Isolation Valves
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
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)
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
Case Study 3: Class 900 Grade 2/2H vs
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)
150 (6) ENG. WALL 1/2" plate 12.7 (0.500) ENG. WALL 3/8" plate 9.525 (0.375)
200 (8) ENG. WALL 5/8" plate 15.875 (0.625) ENG. WALL 1/2" plate 12.7 (0.500)
250 (10) ENG. WALL 5/8" plate 15.875(0.625) ENG. WALL 1/2" plate 12.7 (0.500)
300 (12) ENG. WALL 3/4" plate 19.05 (0.750) ENG. WALL 5/8" plate 15.875 (0.625)
eco
no
mic
s
Piping & Fabrication
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
Class 900 Grade 2H/Class 600 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)
To
tal
Co
st/
To
tal
Co
st
for
Gra
de 1
2,
%
Grade 2H
eco
no
mic
s
Piping, Fabrication & Isolation Valves
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
Pipe, Fabrication and Valves
-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)
To
tal
Co
st/
To
tal
Co
st
of
Gr
12,
%
Gr 2H Pipe & Class 900 Valves
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
TECHNOLOGY