Offshore Engineering

Notch Failure of the Drill String

Surface imperfections in the drill pipe metal greatly affect the fatigue limit of the metal. Imperfections can be mechanical or metallurgical. A notch or pit concentrates the stresses encountered during drilling and speeds the breakdown of the metal structure. They are, therefore, referred to as stress risers, or stress concentrators. Where the notch or pit appears on the drill pipe determines how much it will affect the fatigue limit of the pipe. If a notch is on a portion of drill pipe not subject to stress, the notch has little effect. If a notch is within twenty inches of a tool joint in the pipe’s upset runout, where maximum bending takes place, it can form the nucleus of an early fatigue break.

The shape and type of notch or scratch is also important. A longitudinal notch, an extensive saucer with a rounded bottom, will distribute the stress and be relatively harmless whereas a minute scratch with a sharp bottom will act as a stress riser and lead to failure.

Some steel is more sensitive to notches as other steel; notched brittle steel fails more quickly than ductile steel. Various surfaceNotch Failure of the Drill String 2 dents and scratches that can cause eventual drill pipe failure include the tong marks and slip marks, cuts, scratches, spinning chain marks and scratches, stencil markings, hammer marks, corrosion grooves caused by rubber protectors, electric arc burns, and downhole notching caused by formation and junk cuts.

Of all these defects, tong marks although rare, are probably the most damaging marks produced on drill pipe in the field. They are long, deep, and frequently sharped. Because such notches are longitudinal, they may not lead to notch failure. Even a slight deviation from vertical in the wellbore, however, can change the stress on the pipe and longitudinal notches can become stress concentrators. A change in the wellbore from vertical alters the stress along the defect from longitudinal to transverse. Tongs, therefore, should be applied to the tool joint, never to the body of the drill pipe, because the toll joint is thicker than is the pipe itself. In addition, applying tongs to drill pipe body may crush the pipe as well as notch it.

Rotary slips are made with fine serrations and are used to hold the pipe in place and to prevent it from slipping down into the hole when a connection is being made or broken out. The slips can, however, score the pipe if they are mistreated, worn, or carelessly handled. Slips with worn, mismatched, incorrectly sized, or improperly installed gripping elements can allow one or two teeth or portions of the teeth to catch the full load of the drill string, thereby causing deep notching and potential failure.

Notch Failure of the Drill String 3Inasmuch as any transverse mark can be a dangerous stress concentration point, it is not surprising that steel stencil marks can be the start of fatigue when parts of the letter are transverse to the pipe and the steel stamp is in the wrong place. Never steel stencil on the drill pipe tube.

Corrosion at the top of the rubber pipe protectors can produce a circumferential groove. These grooves can lead to failure. Modern protectors are designed to minimize this risk. Because the protectors usually produce the grooves when they are left on the pipe while the pipe is in storage, the IADC recommends removing them before placing pipe in storage.

Welders sometimes attach the ground lead to the pipe rack instead of to the material being welded. This action is particularly dangerous in that the subsequent arcing between the rail and the drill pipe goes unnoticed. This arcing pits the pipe. Though these pits are small, they are surrounded by a wide band of burned metal that is as hard as glass and they are very prone to rapid fatigue failure.

It is very important that the drilling crew not run bent or crooked pipe into the hole. A crooked joint of pipe is always a potential failure. A crooked Kelly can cause bending in the first joint of drill pipe below the rotary table. If the stress is great enough, failure will occur. Having a crown block off center because the mast or derrick is not plumb can also cause pipe failure because the off-center block throws bending stresses into the Kelly and the drill string.

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Here is the classic reference title intended to be of great practical use for the drilling engineers. The content of the book has been prepared by Stefan Miska and Robert Mitchell, two world recognized experts, applying a very technical approach when compiling the content. As a result of their combined efforts, the book is not difficult to read and the materials contained will be easy to understand even to the beginners; the illustrations and very informative.

We should still note that this is not the best choice for the absolute beginners and the readers are expected to have at least some minimal knowledge in the field. The title of the book says it all. The publication is full of very useful technical information and equations to be used by the practicing drilling engineers.

We would definitely recommend the present title to all people working in the drilling industry and looking for a good and comprehensive technical reference book. The content of the volume has been organized in a pretty sensible fashion and is easy to search. The crystal-clear pictures and informative data diagrams are supplementing the main text part of the book. It is a technical volume ideal for the specialists with moderate engineering experience.

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This book was prepared and released specifically for the offshore industry professionals and students in the field of marine, ocean and coastal engineering, as well as in the field renewable energy and other relevant areas. The author tried to introduce the base for the design of the offshore structures; he addresses the wind and wave energy converters, platforms, wind turbines as well.

The publication created a link between the established and effective theoretical methods of the offshore structure design and calculation, and available recognized standards. The material has been presented in a very simple and easy to understand manner. Some of the most important keywords in the book are offshore structures, structural dynamics and wave energy converters, combined wind and wave energy, energy structures, stochastic methods, wind turbines including floating ones, renewable energy etc.



Definitely recommended for the people engaged in the design and construction of the various offshore structures, making associated calculations and conducting researches in this field since they will find lots of interesting and valuable information in the pages of this volume.



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The present publication was published to encompass all newly introduced novel CFD techniques for the computation of the various offshore wind/tidal applications. The CFD techniques, standing for the computational fluid dynamics, are commonly regarded as one of the basic design instruments used for the exploration of the various engineering challenges that are presented by the turbines for the generation of the energy from winds and tides.

The problem is that the experimental tests in the offshore environment are very difficult to arrange and costly; that is why the industry people have had to concentrate on the CFD as the option to be utilized when designing the appropriate elements of the turbines, to get clear understanding of the physical phenomena involves, be able to predict the production of the electric power etc.



Note that the amount of books dedicated to the offshore turbines for power generation is still very limited so we would you to use this opportunity; we are pretty sure that no one will be disappointed with the content of this volume.



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This is the seventh edition of the popular Primer - it has been significantly expanded and supplemented with more than two hundred of colorful illustrations and photos as well as enhanced graphics and content. The materials presented in the book cover the whole process of drilling a well, from exploration to completion of the well.

The contents as follows - Introduction; History; Cable-tool and rotary drilling; Rotary rig types; People and companies; Oil and gas occurrence and characteristics; The drill site; Rig components; Rigging up; Normal drilling operations; Formation evaluation; Completing the well; Special operations; Environmental concerns and rig safety; Conclusion.

The publication has already proven very helpful when teaching the fundamentals of the oil well drilling to the non-experienced people and newcomers to the industry. The content of the book covers literally all important matters, from conception of the very first derrick and up to the modern and technically sophisticated drilling equipment of today.

The readers will be provided with a well-rounded general information on how the oil well drilling actually takes place. It is very easy to read and follow so may be recommended for the college courses. The graphics are excellent and explanations are kept at a basic level to be easily understood by all people regardless of their experience.

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A new release of maybe the best principle primer of the offshore industry. The present publication has not been originally intended to serve as a definitive manual, it would rather be useful as the overall reference source providing the general technical introduction to the offshore engineering which is quite a complex object. The author's aim was to provide readers with a full coverage of the important aspects of the offshore industry presented in easily understandable terms; his efforts have made this title popular and appreciated by both newcomers to the offshore industry and the experiences practicing engineers.

The content of the publication starts with the general information about the offshore structures and vessels. According to the numerous feedbacks, this title shall be treated as a very valuable and timely addition to any specialist's library. The author has provided superb and lucidly clear technical explanations of the key aspects of the disciplines involved and made the book rick of essential information easily accessible to the readers regardless of their background and experience in the field.

The offshore engineers of today are required to perform a huge number of different tasks; this book shall definitely be on his shelf for ready and quick reference. It will be particularly valuable to the new recruits to the offshore industry and equally appreciated by the experienced specialists willing to refresh their technical knowledge...

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We would definitely say that this book is the best one for those willing to understand the oil and gas industry but having little to no technical skills and experience in the field. The author has provided readers with a broadest perspective on the industry, paying particular attention to the exploration and production of the hydrocarbons in America. You will be taken through all operations taking place in the course of exploration and evaluation of the available resources, up to their production, storage and final delivery to the customers.

The volume mainly focuses on the various equipment and machinery, and all processes and techniques. The oil and gas terms have been provided in the appendix. The author wrote the book trying to avoid any formal and too technical jargon to make reading easier for the newcomers.

All of the important aspects have been covered by the author who did succeed in covering all of those areas in a remarkably informative manner. The book can be used both in the classroom for the students and for the self-study, one can just read it at home to have a good picture of what is happening in the oil and gas industry without having to go too deep into technical details, and this is the main idea of the author.

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Have a look into this excellent set made of two books – A Non-technical Overview and Operations and Practices. The process of preparing these volumes started some decades ago. The first book is actually dealing with the hardware of the petroleum industry, i.e. the vessels serving the industry including so-called OSVs – offshore supply and offshore support vessels, together with their technical characteristics and operations.

The division applied by the author made it possible for the readers to easily select which of the shipping industry aspects is interesting to them. The contemporary tanker business is driven by the logistics. The demand for the oil tankers depends on where exactly the hydrocarbons are consumed; addition to that, the location where the crude oil is produced and refines, is also important.

The material contained in the present book is arranged in twelve separate chapters providing the introduction to the offshore shipping industry and giving valuable insight to the modern tankers, refinery operations, design and operation of the tankers, oil pollution prevention and associated liability, LPG market and many other areas. Some good historical background has been provided by the author so that the readers have a full and clear picture of how the industry developed through years.

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