Developed and formulated by American T.H. Hill company and 36 cooperated companies, DS-1TM standard (3rd edition) is a comprehensive standard which integrating the manufacturing, design and inspection of drill string into one. By application and improvement of 10 years, DS-1TM standard has reached an unprecedented level and become a global standard.

 

DS-1TM comprises of three volumes, i.e. Drilling Tubular Product Specification, Design and Operation of Drill String and Drill String Inspection. Among which, the content pursues comprehensibility and completeness with new concepts, ideas and detailed data as well as graphs in each volume. Also, the edition holds convenience as principle with complete graphs, tables and words. In a word, this standard has reached an unprecedented level.

 

Volume 1 is a totally new, easy to use manufacturing specification for drill tubular products. A global manufacturing standard must be comprehensive, technically sound and easy to use for both buyer and producer. In developing Volume 1 of DS-1TM Third Edition, we have worked with the manufacturers, buyers, and users of the drilling tubular products to create such a standard. The Drilling Tubular Product Specification is Volume 1 of DS-1TM Third Edition, and offers a totally new approach to standardization of the manufacturing process.

 

Volume 1, Specification for Drilling Tubular Goods is featured with the following characteristics:

 

 

Two levels of product specification have been established: normal and critical. The former is equal to the requirements of API Spec 5D and API Spec 7 while the latter level is much stricter at performance and inspection. 

All manufacturing, dimensional and metallurgical requirements in tabular format resulted in easy to check and compare. 

Covers drill pipe, HWDP, subs, drill collars and pup joints. 

Addresses the requirements for higher grade drill pipe (Z-140 AD V-150) which is neglected by API specification. 

Addresses special drill strings, i.e. thick wall thickness drill pipes. 

Includes procedures for non-destructive testing of components not addressed by API. 

Entire volume structured for ease of use. 

Volume 2 is a revolutionary standard for drill string design and operation. Years of research have culminated in a ground-breaking approach to drill string design that maximizes fatigue mitigation while delivering an optimal overall design. This innovative technology can only be found in Volume 2 of Standard DS-1TM Third Edition.

 

Volume 2, i.e. Design and Operation of Drill String, has the following ground breakings:

 

 

A complete creative design method is established to minimize fatigue wearing: curvature index and stability index. Therefore, complex design and calculations is avoided and fatigue wearing rate can be reduced greatly only by checking the tables with design drilling equipments. 

In accordance with risk design principle, over-load design and fatigue wearing design can be divided into 3 design groups which corresponding to different drilling conditions and inspection requirements. 

Addresses the application of new drill pipe sizes and grades. 

The impact of slip mark degree to its fatigue is added which enlarged the scope of slip-cut severity. 

New methods for corrosion monitoring. 

Considerations for reactive torque and casing wear. 

Detailed instructions for specifying an appropriate inspection. 

Volume 3 is a comprehensive product inspection standard providing comprehensive procedural specification, convenient inspection system and technology updating in time. By enlarging the traditional inspection specification and issued in independent volumes, DS-1TM standard (3rd edition) has become a global standard for inspection.

 

 

Volume 3, i.e. Drill Stem Inspection, includes the following new content:

 

 

Inspection tables supplemented with new pipe sizes, weights, and grades as well as coverage of Z and V grade drill pipes with. 

Classify the inspection methods into 31 inspection processes. For specific product inspection, only the inspection processes and acceptance criteria needs to be identified. 

New inspection criteria for thick wall thickness, heavy weight drill pipes and drill collars is added. 

Addresses inspection criteria of private patent products, such as Grant double-shoulder drill pipes, etc. 

Make-up torque table is extended. 

Internal coating evaluation reference photographs. 

New procedure for full length UT inspection of drill pipe tubes. 

New inspection category for heavy duty landing strings. 

Fishing tool inspection criteria. 

DS-1TM has become widely accepted as the standard for inspecting drill string components. Several questions are commonly asked about using the standard. These questions are answered here:

 

Q: “What specific drill stem components are covered by DS-1TM inspection procedures?”

 

A: The Third Edition of the standard covers used drill pipe, HWDP, drill collars, API and similar rotary shouldered connections, a number of proprietary connections, drilling jars, kellys, subs, stablizers, hole openers, underreamers, casing scrapers, roller reamers, safety valves, Kelly valves, IBOP’s, MWD, LWD, fishing tools, heavy duty landing strings, motors and turbines.

 

Q: “What is DS-1TM “registration”? How do I get this done? ”

 

A: You can get your inspection company or threading shop “Registered” by T H Hill Associates, Inc. (or some other registration agency) under DS-1TM. In this process, the registration agency will first review your internal quality assurance processes, your equipment and gage certification procedures, and your program for inspector training and certification. If these comply with applicable ISO, API AND ASNT documents, the registering agency will nest audit your shop to make sure that you are following them. If the results of the audit are acceptable, the registering agency will issue its “Registration” as an indicator that you have established acceptable internal process controls and that you were found in compliance by an audit. In a sense, it’s like ISO certification of a manufacturing facility. It does not guarantee the quality of your services on any specific inspection or threading job, but does show that you’ve established and demonstrated certain internal controls that are important in providing consistent quality to your customers. Form more detailed information and instructions for getting it done, see Chapter 4 of this volume.

 

Q: “How does a DS-1TM inspection differ from an API inspection?”

 

A: Unfortunately, neither one of the two terms in this question has any precise meaning, so the question cannot be answered. The term “API inspection,” although frequently used by people in the industry, has no precise meaning spelled out in any API documents. Thus, different people have different opinions of what “API inspection” actually entails. Neither is the term “DS-1TM inspection” meaningful unless it’s accompanied by a specific Service Category (Number 1-5 or HDLS).

 

Q: Are DS-1TM requirements more rigid than API requirements for drill string inspection?”

 

A: This question must be answered in two parts.

 

First, in terms of the drill pipe attributions required for a component to be accepted under Premium Class or Class 2 acceptance criteria. there is very little difference in the two standards. In fact, the majority of the DS-1TM acceptance criteria were taken directly from API RP7G. However, in terms of inspection process quality control, DS-1TM places firm requirements on how an inspector must calibrate and use his or her equipments. API RP7G at this writing does not address these points at all. Therefore, no comparison is possible in this area.

 

Q: “Can I use Volume 9 of DS-1TM for inspecting new drill string component?”

 

A: No. Volume 3 of the standard applies only to used drill stem equipment. Its procedures are specifically geared to finding service-induced defects, and would not be effective for finding typical manufacturing flaws. For new drill pipe inspection, refer to Volume 1 of this standard. For gaging new tool joints and rotary shouldered connection, see API Specification 7.

 

Q: “ How do I order inspection under DS-1TM?”

 

A: How to order inspection service is covered in detail earlier in this chapter.

 

Q: “My inspection company tells me that it will cost more to do a DS-1TM inspection than an API inspection. Is the extra expenditure justified?”

 

A: This is the most frequent question that arises. It is best answered in the context of DS-1TM Service Categories. When the sponsor committee first established DS-1TM categories, the industry was using an informally defined program that many (but not all) inspection companies called a “Standard Rack Inspection”. This “Standard Rack Inspection”(or its rough equivalent, since its meaning varied by company and location) was adopted by the sponsor committee as DS-1TM Category3. To give inspection buyer some flexibility while maintaining tight control over inspection processes, the sponsor committee also established Categories 1 and 2 (with fewer inspection than Category 3), and Categories 4-5 (with more inspections). If we suppose that by “API inspection” the speaker above really means what was loosely called a “Standard Rack Inspection”, then the cost of that inspection should be nearly identical to DS-1TM Category 3. If it is significantly cheaper, then the inspection company is most likely omitting some process control step required in DS-1TM. Tightening to the DS-1TM quality requirements would almost certainly be justified. 

In more meaningful terms, the comparison could be phrased as “Standard Rack Inspection” vs. “DS-1TM Category 3 inspection”. Unless the company is omitting some step required by DS-1TM, the cost should be the same. Of course, if the comparison were made with a DS-1TM Category 4 or 5 inspection program, the latter should cost more. Conversely, a DS-1TM Category 1 or 2 program should cost less. For more on relative inspection costs, see Volume 3.

 

Q: “My company has standardized on DS-1TM Category 5 inspection program for all components, but inspection costs have increased. Are we doing the right thing?”

 

A: Probably not. The cost of a Category 5 inspection is roughly twice that of the normal program represented by Category 3. Category 5 is intended for drill string components that are to be used in extremely adverse condition where the potential cost of a failure is very large. Unless your drilling conditions are risk management policies dictate the utmost caution, Category 5 may not be justified.

 

Q: “I would like to quality my drill string by checking a sample. What percent of the string just I inspect to be sure that it is all acceptable?”

 

A: You should not inspect your drill string by checking a sample. Unless the sample you choose is truly representative of the entire lot of components, and unless you hav zero reject rate in your sample, you cannot be fully confident that every single component in the unchecked portion is acceptable. In a nutshell, if you need to do an inspection at all, you should apply it to all of the pipe in the lot. If you need to reduce inspection costs in low-risk situations, you might consider dropping to a lower service category.

 

Q: “ Under what conditions could spot sampling be considered good practice?”

 

A: Spot sampling is useful if you wish to get a general feel for the condition of a lot of pipe, without qualifying every individual pieces. For example, if you were concerned with about the general condition of a string, you might use spot checking to decide whether to proceed with inspecting that string or to look for an entirely different string.