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Rio Oil & Gas Expo and Conference 2022
ISSN 2525-7579
Conference Proceedings homepage: https://biblioteca.ibp.org.br/riooilegas
Technical Paper
Metallic materials for valves applied in Oil & Gas
industry
Diógenes Barbosa Teles 1
Jose Francisco Mariano 2
André João de Souza 3.
1. MICROMAZZA, ENGENHARIA, . VILA FLORES - RS - BRASIL, dbteles@ucs.br
2. MICROMAZZA, ENGENHARIA, . VILA FLORES - RS - BRASIL, mariano@micromazza.ind.br
3. UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL, DEMEC, . PORTO ALEGRE - RS - BRASIL, ajsouza@ufrgs.br
Abstract
The manufacturing of industrial valves presents a diversity of normative specifications of metallic materials for its
components used in the exploration, production, refining, and transportation of petroleum products. The manufacturers
carry out manufacturing according to the normative requirements and customer requests while the users perform the
correct selection and specification of materials according to applicability. Thus, the different information variables between
the valve manufacturer and the equipment designer make the selection of materials complex. In this context, this paper
presents a review of the current literature: standards, technical/scientific articles, national and international specifications,
referring to the prime metallic materials used in the manufacture of ball valve components, applied in the oil and gas
industry, and that makes the function of containing and/or controlling the working pressure of fluids in operations. This
study presents as a supporting reference, for the understanding and decision-making regarding the selection of metallic
materials, with information related to properties, tests, standards, and applications.
Keywords: Ball valve. Valve components. Valve materials. Alloy steels. Literature review
Received: October 06, 2021 | Accepted: August 25, 2022 | Available online: September 26, 2022
Article nº: 071
Cite as: Proceedings of the Rio Oil & Gas Expo and Conference, Rio de Janeiro, RJ, Brazil, 2022.
DOI: https://doi.org/10.48072/2525-7579.rog.2022.071
© Copyright 2022. Brazilian Petroleuma and Gas Institute - IBP This Technical Paper was prepared for presentation at the Rio Oil & Gas Expo and Conference, held in September 2022, in Rio de Janeiro. This Technical Paper was selected
for presentation by the Technical Committee of the event according to the information contained in the final paper submitted by the author(s). The organizers are not supposed to translate or correct the submitted papers. The material as it is
presented, does not necessarily represent Brazilian Petroleum and Gas Institute’ opinion, or that of its Members or Representatives. Authors consent to the publication of this Technical Paper in the Rio Oil & Gas Expo and Conference 2022
Proceedings.
Metallic materials for valves applied in Oil & Gas industry
Rio Oil & Gas Conference, 2022. | ISSN 2525-7579 2
1. Introduction
Industrial valves are mechanical equipment designed to direct, start, block, control, mix and
regulate a process fluid's flow, pressure, or temperature. They are applied in all industries that require
liquid and gas management in their production processes, such as oil and gas, pulp and paper, chemical,
nuclear, food, and others (Skousen, 2011).
Among the various production sectors involving fluids handling, the oil and gas sector presents
a wide variety of national and international standards and specifications. These standards cover
constructive aspects of the product, present groups of materials for component manufacturing, and
regulate factory acceptance tests, inspections and qualifications. Due to the high criticality of
petrochemical applications, professionals in the field must know a lot about valve functionality,
normative requirements, and properties of the materials used. In this way, it can be expected that the
required results will be achieved in the production process (Teles et al., 2020).
According to the research report N° 162, carried out by the Offshore Division of Health & Safety
Executive (HSE) (2003), in the United Kingdom, most failures related to valves in operation are
associated with incorrect selection of the valve type and materials. In a group of 253 valves analyzed,
which presented defects in operation, 43% of the investigated causes were related to problems, such
as internal/external corrosion, mechanical failure, mechanical fatigue, and metallurgical defects
present in the materials.
Currently, the industrial valve application requirements in the Oil & Gas sector have been
increasing in Brazil and worldwide, especially in deepwater exploration and processing in floating
storage and transfer units, called: Floating Production Storage and Offloading (FPSO). These
processing units have to receive production from subsea oil wells and process them to stabilize oil and
separate the produced water and natural gas. In this process, equipment is often subjected to highly
corrosive environments, with the presence of chemical compounds, such as carbon dioxide (CO2) and
hydrogen sulfide (H2S) (Oliveira & Zoghbi Filho, 2016).
In addition to the corrosive environment, valves subjected to the crude oil separation process,
for example, in some cases, also need to be resistant to high temperatures, in the range of 200 °C to
400 °C (Jablonski & Helfer, 2019).
In order to overcome the mentioned limitations associated with the petrochemical industry
applications, the valves are specified and produced in several groups of metallic alloys. The equipment
configurations can use a carbon steel body and stainless steel internal components. For applications
with greater criticality in terms of the corrosive effect of the fluid, all the metallic components of the
valve are made of stainless steel, which can be from the groups: martensitic, austenitic, duplex, and/or
super duplex (DR-ENGP-I-1.1, 2019) (ASME 16.34, 2020).
Therefore, this article presents some aspects related to the equipment operations, the
nomenclature of the main components, and the detail on material groups most used in manufacturing
parts containing pressure (PC) and parts controlling pressure (PR) from industrial ball valves.
2. Ball valve
A ball valve is essentially an on-off operator, where a ball is used as an obturator with a through-
hole. This component describes a rotational movement from 0° to 90° about the fluid flow direction in
the pipe or vessel to open and close. The ball passage hole is fully aligned with the pipe in the open
position, allowing the fluid to flow, and the ball orifice is perpendicular to the flow direction in the
closed position, blocking the fluid passage (Mathias, 2014) (Silva, 2010). More specifically, the
sealing system of the ball valve with the seat can have two constructive patterns: floating and trunnion
(Dickeson, 1999) (Smith & Zappe, 2004).
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2.1. Trunnion ball valve
In the trunnion, the ball is bi-supported by axes, where the sealing component is called the seat
ring. This part moves in piston effect, performing the upstream sealing at the valve's internal cavity
entrance. The trunnion at the bottom and the stem at the top affect the ball bearings, which rotate the
obturator to open/close positions. The efforts are absorbed by self-lubricating bearings, minimizing
the friction during valve operations. The vertical centerlines of the ball and valve body remain aligned.
The trunnion concept, in addition to the upstream sealing, allows fluid-tightness in both flow
directions, performing the sealing called the double block (Dickeson, 1999) (Smith & Zappe, 2004)
(Teles, 2016). Figure 1 shows a sketch of a trunnion ball valve, indicating its main components. The
metallic items that contain the pressure are the body (1) and cover (6), and the internal components
that control the pressure are the ball (2), stem (3), seat ring (5), and trunnion (7).
Figure 1 – Trunnion ball valve components: (1) body, (2) ball, (3) stem, (4) handle, (5) seat ring, (6) cover, (7) trunnion.
Source: adapted from Micromazza (2022).
2.2. Floating ball valve
This design allows freedom of movement of the ball that, in the closed position, floats moving
towards the sealing ring. A slight displacement of the ball's central vertical axis for the valve's central
vertical axis occurs during the flow obstruction process. When the flow pressure is applied upstream,
at the valve inlet, the ball moves, compressing the seat ring and sealing downstream, at the valve
internal cavity exit (Dickeson, 1999) (Smith & Zappe, 2004) (Teles et., 2016). Figure 2 shows a sketch
of a floating ball valve, indicating its main components.
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Figure 2 – Floating ball valve components: (1) cover, (2) ball, (3) stem, (4) handle, (5) seat ring, (6) body.
Source: adapted from Micromazza (2022).
3. Ball valve standards and specifications
The norms defined as constructive standards are part of the history of the evolution of industrial
valves. The requirements in these regulations have the function of guiding the equipment designers
and making the valves (interchangeable) anywhere in the world, ensuring a high degree of safety for
applications. The main standards and complementary specifications currently used by the
petrochemical and natural gas industry are presented below.
3.1. Constructive standards
The primary standards related to ball valves applied in the oil industry are summarized in the
topics:
API 6D (2014) presents material specifications, testing requirements, limits of chemical
compositions, and indicates other specific standards for each topic related to materials. Its scope
covers gauges from ½" to 60", in pressure classes: 150, 300, 600, 900, 1500, and 2500;
ISO 17292 (2015) is related to metal ball valves in nominal diameters from ¼" to 24" for pressure
classes: 150, 300, 600, and 800. For valves in class 800, the standard covers only valves with
threaded and welded ends;
ASME 16.34 (2020) exhibits the groups of materials, definitions of pressure classes, indications of
complementary standards for testing and inspection. The pressure class is designated by this
standard as an adimensional number related to temperature ranges and maximum working
pressures, that can be used in a valve, according to the material used in the manufacture of the
equipment body;
ABNT NBR 15827 (2018) describes the selection of materials for ball valves according to the
manufacturing process, as it specifies forged material for the manufacture of the body of small
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diameter valves, ½" to 1.1/2", for pressure classes equal and greater than 800. The material obtained
by casting is acceptable for larger valves, such as 2" to 42" sizes for pressure classes 150 and 300.
It also presents a material specification for manufacturing the prototype valve for product
homologation testing. For this type of qualification, the material specification for the ball valve
recommends the body in carbon steel and the internal components in stainless steel with 13%
chrome in its composition;
ASME Division 2 (2021) and ASME Section 2 Part D (2021) show the criteria for analyzing the
allowable stresses and properties of the materials used in the valve components. These requirements
are used as design assumptions when preparing calculation memorials;
NACE MR175 (2015) and ISO 15156 (2020) define requirements and recommendations for the
selection of alloys steel with high corrosion resistance, for services on oil and natural gas platforms,
in environments containing the presence of highly corrosive agents, such as hydrogen sulfide (H2S);
DR-ENGP-I-1.1 (2019) refers to a material standardization guideline. Prepared by PETROBRAS,
this specification relates to valves and piping fittings.
The specific standards for metallic materials are part of the American Society for Testing and
Materials (ASTM) collection and will be addressed in the following items of this article.
3.2. JIP 33 – Supplementary specifications
Oil and gas operators often ask suppliers, manufacturers of valves and equipment, to meet a
different set of specific requirements for each order. Extensive specifications are often provided to fill
specific gaps in the traditional construction standards. The specifications may differ even when applied
to the same project from the same company. This system tends to make the process inefficient. The
standardization of specifications used to acquire equipment can make the supply chain faster, with
higher quality and lower cost. In this context, the International Association of Oil and Gas Producers
(IOGP) started the program called Joint Industry Program 33 (JIP33) in 2016, with the support of the
World Economic Forum (WEF). The program participates in the world's largest companies in the Oil
& Gas segment (JIP33, 2022). Available at <https://www.iogp-jip33.org/about/>. Accessed on: 16
Feb. of 2022.
By 2021, more than 40 specifications for various equipment have been published by the JIP 33
program. Operators are currently implementing them in large projects where the benefits are already
being demonstrated. Related to trunnion ball valves are the following specifications.
IOGP S-562Q (2019) refers to the specification of quality requirements for the supply of ball valves,
including manufacturer's quality management system requirements, buyers' conformity assessment
activities, traceability requirements, and evidence of conformity. It has its references in ISO 9001
(2015), API Specifications Q1 (2013), and IOGP S-562 (2019) standards;
IOGP S-562 (2019) presents additional API 6D (2014) construction standard ball valves
requirements. It contains design, manufacturing, assembly, testing, and documentation
requirements for trunnion ball valves. Covers applications such as piping systems, process plants,
hydrocarbon pipeline systems, gas transmission, distribution, and other oil and gas industry
applications;
IOGP S-563 (2018) is a collection of material data sheets to manufacture components used in valves
and piping systems. It addresses the specific requirements for materials exposed in acidic
environments, as defined by NACE MR175 (2015) and ISO 15156 (2020) standards. Some
specified materials are carbon steel, austenitic and duplex stainless steels, and nickel and titanium
alloys. However, it does not provide guidelines for selecting the material aiming at a specific
service; it is up to the equipment designer to analyze and select the appropriate material for each
required application.
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4. Materials for ball valve component manufacturing
The material groups used for manufacturing ball valve components are presented in ASME 16.34
(2020). This standard divides the alloys material into groups, according to their chemical composition,
indicating the specific standards for each alloy steel, according to its process of obtaining and
manufacturing, for example, castings and forgings, which are the most used.
Carbon steel is generally used in valve bodies, and its function is to contain pressure. It is steel
whose nominal composition is described by (C-Si). The ASTM A105 (2021) specification is used
for the forged material, and the ASTM A216 (2021) WCB grade is applied for the casting version.
Due to its low corrosion resistance, in some cases, metallic or polymeric coatings are used in the
internal interfaces, which have contact with the fluid. These coatings are usually made through the
overlay cladding welding process, using anticorrosive superalloys based on nickel-chromium, like
UNS N06625 or polymeric coatings based on PTFE and ECTFE (Rasador & Teles, 2017).
Martensitic stainless steel is usually applied in internal components of valves; these items have the
function of controlling pressure or flow in the equipment, such as stem, ball, and pistons. It is a
steel with about 13% chromium in its composition, normative standard: ASTM A 182 (2021) grade
F6A for forged material and ASTM A217 (2020) grade CA15 for casting version.
Austenitic stainless steel is utilized in manufacturing parts that contain and control pressure. The
compositions (18Cr-8Ni) and (16Cr-12Ni-2Mo) stand out among these alloys. They have good
corrosion resistance, and the normative standards used are ASTM A182 (2021), grades F304 and
F316 for forging, and ASTM A351 (2018), grades CF8 and CF8M for casting.
Duplex stainless steel is employed to manufacture external and internal valve components. This
alloy has a two-phase microstructure with balanced proportions of austenite (γ - face-centered
cubic) and ferrite (α – body-centered cubic). They are widely used in offshore applications that
require high corrosion resistance and excellent mechanical strength. Diverse alloying elements are
present, mainly Cr, Ni, and Mo (IMOA, 2014). The most used of this family of steels is UNS
S31803, with nominal composition (22Cr-5Ni-3Mo-N). Adding other alloying elements such as Cu
and W, it has a super duplex, which is more resistant to chloride corrosion. The UNS S32760 with
the nominal composition (25Cr-7.5Ni-3.5Mo-N-Cu-W) stands out in this alloy. Although it presents
a series of advantages in the applications, this stainless steel has low machinability due to the high
presence of alloying elements, low thermal conductivity, high temperatures in the cutting zone, high
degree of work hardening, and the generation of a small cutting-section area (thin chips) due to the
low cutting parameters that are generally used. They usually have a higher production cost (Teles,
Policena & Souza, 2021). The standards and grades of these materials most commonly used for
valve component applications are ASTM A995 (2020) grades CD3MN and CD3MWCuN for
castings and ASTM A182 (2021) grades F51 and F55 for forgings.
Table 1 shows a list of the leading materials used to manufacture valve components, and Table
2 exhibits examples of ball valve applications according to the configurations of materials used in the
external and internal components. The suggestions of applications come from good practices
recommended by current literature, such as standards and specifications of oil and gas corporations.
Metallic materials for valves applied in Oil & Gas industry
Rio Oil & Gas Conference, 2022. | ISSN 2525-7579 7
Table 1 – List of material groups used to manufacture valve components.
Group:
ASME
16.34
(2020)
Nominal
composition
Specification
casting process
Specification forging
process
Application
components
Classification
1.1
C-Si
ASTM A216 WCB
ASTM A105
Body and cover
Carbon steel
Note 1
13Cr
ASTM A217 CA15
ASTM A182 F6A
Internal
components
Martensitic
2.1
18Cr-8Ni
ASTM A351 CF8
ASTM A182 F304
Body, cover and
internal
components
Austenitic
2.2
16Cr-12Ni-2Mo
ASTM A351 CF8M
ASTM A182 F316
Body, cover and
internal
components
Austenitic
2.8
22Cr-5Ni-3Mo-N
ASTM A995
CD3MN
ASTM A182 F51
Body, cover and
internal
components
Duplex
2.8
25Cr-7,5Ni-
3,5Mo-W-N
ASTM A995
CD3MWCuN
-
Body, cover, and
internal
components
Super Duplex
2.8
25Cr-7,5Ni-
3,5Mo-N-Cu-W
-
ASTM A182 F55
Body, cover, and
internal
components
Super Duplex
Note 1: material not used for parts containing pressure, such as body and cover; it is not shown in the ASME 16.34 (2020)
material groups.
Source: adapted from ASME 16.34 (2020).
Table 2 – List of material groups used to manufacture valve components.
N°
Body/cover
Internal components
Applications
1
WCB/A105
CA15/F6A
General use, water, inert gases.
2
WCB/A105
CF8M/F316
General use, hydrocarbons, fuels.
2
CF8/F304
CF8/F304
Hydrocarbons, oils, refrigerants.
3
CF8M/F316
CF8M/F316
Chemical processes, hydrocarbons, produced water.
4
CD3MN/F51
CD3MN/F51
Chemical processes, hydrocarbons, seawater.
5
CD3MWCuN/F55
CD3MWCuN/F55
Chemicals, hydrocarbons, seawater, chlorides.
Source: adapted from Micromazza (2022).
Metallic materials for valves applied in Oil & Gas industry
Rio Oil & Gas Conference, 2022. | ISSN 2525-7579 8
5. Conclusion
The present work presented a brief literature review about the primary material specifications
for manufacturing valve components for the oil and gas industry. Some conclusions obtained in this
study are pointed out as follows.
A specification containing only normative requirements according to traditional construction
standards often does not contain the requirements to meet a specific application;
Carbon steel can be applied to the parts containing the pressure of a ball valve, such as the body
and cover. But they are not recommended for the manufacturing of the internal components such
as stem, ball, and seats;
Martensitic steels are recommended for the manufacture of internal valve components but are not
recommended for the manufacture of external parts, which have the function of containing pressure;
It is up to the equipment designer to be aware of the constructive aspects of the valves, the applicable
standardization, and the complementary requirements to carry out the correct selection of the
equipment according to the application data. It is also essential to be aligned with the valve
manufacturer about the needs of the end customers' applications;
There is a worldwide trend in the standardization of equipment specifications for the Oil & Gas
industry, with the emergence of complementary specifications prepared by IOGP;
It is understood that the specification by the buyer and the compliance by the valve manufacturer
of the complementary requirements according to IOGP S-562 (2018) and IOGP S-563 (2019), can
provide a greater degree of safety in specific applications;
It is concluded that standardization of complementary technical specifications according to
international guidelines is beneficial for improving design schedules and can provide better product
performance in applications.
6. Acknowledgments
Special thanks to Micromazza company, manufacturer of industrial valves, for providing
materials and relevant information to prepare this article.
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