Stress Concentration Factor

Stress Concentration Factor

Definition(s)

Stress Concentration Factor

Equal to the local peak stress in a component (including welds) divided by the nominal stress in the component cross-section at the location of the local peak stress.

Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global Standards

Stress Concentration Factor (SCF)

Local peak alternating stress in a component (including welds) divided by the nominal alternating stress in the pipe wall at the location of the component.
  • NOTE: This factor is used to account for the increase in the stresses caused by geometric stress amplifiers that occur in the riser component.
Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Stress Concentration Factor (SCF)

Local peak alternating stress in a component (including welds) divided by the nominal alternating stress in the pipe wall at the location of the component.
  • NOTE: This factor is used to account for the increase in the stresses caused by geometric stress amplifiers, which occur in the riser component.
Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Stress Concentration Factor

Factor relating a nominal stress to the local stress at a detail. NOTE Adapted from ISO 19902:2007, definition 3.50. Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards
Strength

Strength

Definition(s)

Strength

Mechanical property of a material, usually given in units of stress. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Stab Sub

Stab Sub

Definition(s)

Stab Sub

Male half of sealing mechanism between component interfaces. NOTE Stab subs can use elastomeric or metal seals or both. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Splash Zone

Splash Zone

Definition(s)

Splash Zone

The area of the structure that is intermittently wet and dry due to wave and tidal action. Source: API RP 2SIM, Structural Integrity Management of Fixed Offshore Structures, First Edition, November 2014. Global Standards

Splash Zone

Part of the riser subjected to repeated wetting and drying by seawater. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Splash Zone

part of a structure that is intermittently exposed to air and immersed in the sea Source: ISO 19900:2013, Petroleum and natural gas industries – General requirements for offshore structures. Global Standards  

Splash Zone

The external surfaces of the unit that are periodically in and out of the water. The determination of the splash zone includes evaluation of all relevant effects including influence of waves, tidal variations, settlements, subsidence and vertical motions, see Sec.10 B200. Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global Standards  

Splash Zone

That part of the external structure above the boot topping zone subject to wet and dry conditions. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 8, Corrosion Controls, June 2013, Lloyd’s Register, Global Standards
Spider

Spider

Definition(s)

Spider

Device having retractable jaws or dogs used to support the riser on the uppermost connector support shoulder during running of the riser. NOTE The handling spider sits either on the rotary bushing or in the rotary table. It provides a hang-off point for the integral C/WO riser. Some spiders will lock to the rotary via the kelly drive pinholes in the master bushing. With the pins engaged, the spider can resist torque. For non-integral risers, tubing slips and false rotaries are used in lieu of the spider. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Spider

A device for the purpose of suspending tubular goods of any type from the drilling structure, not capable of being used as elevators, that have some element on the internal diameter to grip the outer diameter surface of the pipe body of various tubular goods, that are operated manually or by spring(s) and/or pneumatic or hydraulic power or other assist device or method.

Source:API SPECIFICATION 7K, Drilling and Well Servicing Equipment, Sixth Edition, December 2015. Global Standards
Specified Minimum Yield Strength

Specified Minimum Yield Strength

Definition(s)

Specified Minimum Yield Strength

Minimum yield strength at room temperature prescribed by the specification or standard under which the material is purchased. Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global Standards Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Specified Minimum Yield Strength (SMYS)

The minimum yield strength prescribed by the specification or standard under which the material is purchased. Source: Offshore Standard DNV-OS-C101, Design of Offshore Steel Structures, General (LRFD Method, Det Norske Veritas, April 2011. Global Standards
S-N Curve

S-N Curve

Definition(s)

S-N Curve

Quantitative relationship between the fatigue stress, S, and the number of cycles, N, corresponding to a specific probability of failure for a detail, derived from test data.

Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global Standards

S-N Curve

A plot of stress range (S) against the number of cycles (N) to failure obtained by cycling specimens to failure. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

S-N Curve

Graphical presentation of the dependence of fatigue life, N, on fatigue strength, S. NOTE It is also known as the Wöhler curve. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Slick Joint

Slick Joint

Definition(s)

Slick Joint

Riser joint of standard length without attached buoyancy.

Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards

Slick Joint

Special riser joint designed to prevent damage to the riser and control umbilical where they pass through the rotary table. NOTE Usually included in C/WO risers and is sometimes named “cased wear joint”. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Shearing Valve

Shearing Valve

Definition(s)

Shearing Valve

Gate valve or ball valve designed to shear wireline or coiled tubing and that can seal the bore. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Service Life

Service Life

Definition(s)

Service Life

Duration of time in which the equipment performs under the specified design conditions, i.e. time in active connected riser operations, excluding storage periods.
  • NOTE: The service life is normally a small fraction of the design life.
Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global Standards

Service Life

Duration of time in which the equipment performs under the specified design conditions, i.e. time in active operation excluding storage periods.
  • NOTE: The service life is normally a small fraction of the design life.
Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Service Life

Specified time during which the umbilical system shall be capable of meeting the functional requirements. Source: API SPEC 17E, Specification for Subsea Umbilicals, Upstream Segment, Fourth Edition, October 2010. Global Standards  

Service Life

Period of time during which the flexible pipe fulfils all performance requirements. Source: API SPEC 17J, Specification for Unbonded Flexible Pipe, Third Edition, July 2008. Global Standards
Secure Status

Secure Status

Definition(s)

Secure Status

Establishment of two independent barriers between the reservoir and the environment. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Secondary Load

Secondary Load

Definition(s)

Secondary Load

Load induced by structural deformation (or the prevention thereof) in the riser which is necessary to satisfy the laws of compatibility of strain and deformation. NOTE The internal forces induced by a secondary load diminish when yielding occurs. Secondary loads do not have to be taken into account where they do not affect the resistance of the member/component to resist other loads. Preload of bolts in flanges is an example. During make-up of a flange, the torque/tension applied by the tool on the bolts is primary, but after make-up, the residual bolt preload is secondary. EXAMPLE An example of a secondary load is the bending caused in the C/WO riser during operation within the drilling riser due to flex joint/ball joint angles. Bending moments that exceed yield, in this case, do not generally cause excessive yielding and failure. Other examples are differential temperature in restrained sections and residual stresses after welding. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Wave Scatter Diagram

Wave Scatter Diagram

Definition(s)

Wave Scatter Diagram

Table listing occurrence of sea-states in terms of significant wave height and wave peak period or mean upcrossing period. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Rotary Table

Rotary Table

Definition(s)

Rotary Table

Device used to apply torque to the drill string during drilling and normally located in the centre of the drill floor. NOTE Can be rotated and can support wear bushing or spider. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Rotary Table

A device through which passes the bit and drill string and that transmits rotational action to the kelly. Source: API RP 59, Recommended Practice for Well Control Operations, Second Edition, May 2006. Global Standards Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards  
Riser System

Riser System

Definition(s)

Riser System

The riser and all integrated components, including subsea and surface equipment. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Riser System

Comprises the riser and all integrated components including subsea and surface equipment. EXAMPLE In tubing hanger mode, the system includes all components from tubing hanger to the top drive; in tree mode, the system includes all components from the wellhead to the top drive. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Riser System

The riser together with its supports, component parts and ancillary systems such as corrosion protection, mid water arch, bend stiffeners, buoyancy modules, bend restrictors, bend stiffener latching mechanisms, etc. Source: Rules and Regulations for the Classification of Mobile Offshore Units, Part 3, Functional Unit Types and Special Features, June 2013, Lloyd’s Register, Global Standards
Riser Pipe

Riser Pipe

Definition(s)

Riser Pipe

Seamless pipe which forms the principal conduit of the riser joint. EXAMPLE The riser pipe is the conduit for containing the production fluid flow from the well to the surface tree. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Riser Pipe

Seamless or electric-welded pipe that forms the principal conduit of the riser joint. NOTE The riser main tube is the conduit for guiding the drillstring and containing the return fluid flow from the well. Source: ISO 13624-1:2009, Petroleum and natural gas industries – Drilling and production equipment – Part 1:Design and operation of marine drilling riser equipment. Global Standards  
Riser Model

Riser Model

Definition(s)

Riser Model

Structural model which is established from the tabulated data of the riser, to describe the actual riser, and used in global analysis of the riser system. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Riser Model

Structural model, established from the tabulated data of the riser, to describe the actual riser, and used in a global analysis of the riser system. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Return Period

Return Period

Definition(s)

Return Period

Average period of time between occurrences of a given event. NOTE The inverse of return period expressed in years is the statistical probability of such an event occurring in any given year Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Return Period

Average period of time between occurrences of a given event. NOTE The inverse of the return period is the statistical probability of such an event occurring in any given year. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Return Period

Average period between occurrences of an event or of a particular value being exceeded. NOTE The offshore industry commonly uses a return period measured in years for environmental events. The return period is equal to the reciprocal of the annual probability of exceedance of the event. [ISO 19901-1:2005] Source: API RP 2MET, Derivation of Metocean Design and Operating Conditions, First Edition, November 2014. Global Standards Source: ISO 19901-7:2013, Petroleum and natural gas industries – Specific requirements for offshore structures – Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units. Global Standards Source: ISO 19900:2013, Petroleum and natural gas industries – General requirements for offshore structures. Global Standards  

Return Period

Average period between occurrences of an event or of a particular value being exceeded. NOTE The offshore industry commonly uses a return period measured in years for environmental events. The return period in years is equal to the reciprocal of the annual probability of exceedance of the event. [ISO 19901-1:2005, definition 3.23]. Source: ISO 19905-1:202, Petroleum and natural gas industries – Site-specific assessment of mobile offshore units – Part 1: Jack-ups. Global Standards
Retainer Valve

Retainer Valve

Definition(s)

Retainer Valve

Valve assembly in the C/WO riser used to retain fluid within the riser and hence preventing its escape to the environment during a riser disconnect operation. NOTE Typically located just above the disconnect point. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Resistance

Resistance

Definition(s)

Resistance

Mechanical property of a component, a cross-section, or a member of the structure, e.g. bending resistance, local buckling resistance. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Resistance

Capacity of a structure, a component or a cross-section of a component to withstand action effects without exceeding a limit state. NOTE This definition is at variance with that specified in ISO 19900:2002. Source: ISO 19901-7:2013, Petroleum and natural gas industries – Specific requirements for offshore structures – Part 7: Stationkeeping systems for floating offshore structures and mobile offshore units. Global Standards  

Resistance

capacity of a component, or a cross-section of a component, to withstand action effects without failure Source: ISO 19900:2013, Petroleum and natural gas industries – General requirements for offshore structures. Global Standards
Re-Entry Spool

Re-Entry Spool

Definition(s)

Re-Entry Spool

Uppermost part of a subsea tree to which the C/WO riser is attached to gain vertical well access or the uppermost part of a lower workover riser package to which an emergency disconnect package connector is attached to provide a single disconnect point. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Re-Entry Spool

Tree upper connection profile, which allows remote connection of a tree running tool, LWRP or tree cap. Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards
Ratcheting

Ratcheting

Definition(s)

Ratcheting

Progressive inelastic deformation or strain which can occur in a component that is subjected to variations of mechanical stress, thermal stress, or both (thermal stress ratcheting is partly or wholly caused by thermal stress). NOTE Ratcheting results in a plastic deformation, which increases by about the same amount at each cycle and quickly leads to an unacceptable value. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Prying

Prying

Definition(s)

Prying

Magnification of an external load by a pseudo-lever action when the load is an eccentric tensile load. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Process Shutdown

Process Shutdown

Definition(s)

Process Shutdown

Controlled sequence of events that ensures that the well is secured against accidental release of hydrocarbons to the environment. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Peak Stress

Peak Stress

Definition(s)

Peak Stress

Part of stress, which is additive to the respective primary and secondary stresses, to form the total stress. NOTE Peak stresses do not cause any noticeable distortion and are only important to fatigue and brittle fracture in conjunction with primary and secondary stresses. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Peak Stress

A peak stress is a highly localized stress that exists at a discontinuity in the load path. An example of a peak stress is the high localized stress at the root of a thread in a bolt. Source: API SPEC 16R, Specification for Marine Drilling Riser Couplings, Exploration and Production Department, First Edition, January 1997. Global Standards
Qualified Personnel

Qualified Personnel

Definition(s)

Qualified Personnel

Individuals with characteristics or abilities gained through theory and training and/or experience as measured against the manufacturer’s established requirements. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Qualified Personnel

Individual with characteristics or abilities gained through training, experience, or both, as measured against the established requirements of the manufacturer/purchaser/this International Standard. Source: API SPEC 6A, Specification for Wellhead and Christmas Tree Equipment, Twentieth Edition, October 2010 (Addendum November 2012). Global Standards  

Qualified Personnel

Individual with characteristics or abilities gained through training, experience or both, as measured against the manufacturer's established requirements. Source: API SPEC 16A, Specification for Drill-through Equipment, Third Edition, June 2004 (Errata/Supplement November 2004). Global Standards  

Qualified Personnel

Individuals with characteristics or abilities gained through training, experience, or both, as measured against the manufacturer/user/API established requirements. Source: API SPEC 16C, Specification for Choke and Kill Systems, First Edition, January 1993 (Reaffirmed 2001). Global Standards  
Out-of-Roundness

Out-of-Roundness

Definition(s)

Out-of-Roundness

Deviation of the circumference from a circle. NOTE This can be an ovalization, i.e. an elliptic cross-section, or a local out-of-roundness, e.g. flattening. The numerical definition of out-of-roundness and ovalization is the same. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Out-of-Roundness

Difference between the maximum and minimum diameters of the bar or tube, measured in the same crosssection, and not including surface finish tolerances outlined in 8.1.4. Source: API SPEC 7-1, Specification for Rotary Drill Stem Elements, First Edition, March 2006 (Addendum April 2011). Global Standards  
Operating Mode

Operating Mode

Definition(s)

Operating Mode

Conditions that arise from the use and application of the equipment or riser system. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Operating Mode

Condition that arises from the use and application of the equipment or riser system. NOTE Typical operating modes are racking of riser components, running/retrieval, landing/connecting, overpull to verify lockdown, system pressure testing, normal operation, surface shut-in, subsea shut-in, disconnecting, hang-off, overpull to retrieve tubing hanger, failure of dynamic positioning system, failure of tensioner system and failure of anchors or anchor lines. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Operating Envelope

Operating Envelope

Definition(s)

Operating Envelope

Limited range of parameters in which operations will result in safe and acceptable equipment performance. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  
Notch Stress Range

Notch Stress Range

Definition(s)

Notch Stress Range

Sum of the primary stress range plus the secondary stress range plus the peak stress range, forming the total stress range (see Annex C), as applied to fatigue assessment of unwelded parts. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards