US2119698A - Sucker rod and process of manufacturing the same - Google Patents

Description

Patented June 7, 1938 SUCKER ROD AND PROCESS OF MANUFAC- TURING THE SAME Frank B. Bayle'ss, Oil City, PaQassignor to Oil Well Supply Company, Dallas, Tex., a corporation of New Jersey No Drawing. Application July 6, 1935,

Serial No. 30,170

' 2 Claims.

My present invention relates to an alloy resistant to corrosion by mineral acids, such as sulphuric and hydrochloric acids, and to corrosive compounds, such as salt or saline waters, of hy- 5 drogen sulphide. It relates particularly to an alloy that may be hardened to give it an increased, tensile strength suitable for the construction of oil pumping equipment, such as pumping elements, sucker rods, connectors, tubing, etc., and remain resistant to hydrogen sulphide or organic sulphides, and to saline waters occurring in certain oil wells.

Pumping equipment, such as sucker'rods for operating the pumps of deep oil wells, must have Y a, high elastic limit inasmuch as they must support the column of oil standing in the tubing as well as the weight of the sucker rods and pumplng mechanism.

During the pumping of the well the sucker rod, and certain other pump elements, are subjected to periodic stresses as the pump moves in its al-. ternate upward and downward strokes. r necessity for obtaining a high elastic limit and the recurrent stress modifications render the sucker rods and similar equipment particularly susceptible to the corrosive action of sulphides and saline or acidic substances present in the oil from some fields.

My present invention provides an alloy, and sucker rods and other equipment made from suchalloy, having an added resistance to corrosion under the conditions prevailing in oil wells, and also of general application as a corrosion resisting alloy for other purposes.

The invention also provides methods whereby the alloy may be suitably worked and shaped to obtain the various articles into which it is to be made.

The corrosion resistant alloy of my invention is formed of a substantially pure iron to which limited quantities or proportions of nickel and molybdenum have been added. The percentage of nickel in the alloy is preferably about 3.50%, or from 3.35% to 3.75%. The percentages may, however, vary somewhat from these optimum percentages. The lowest limit that may be used is 2%, and thehighest about 5% The percentage of molybdenum is between 0.15% and 0.30%. The percentage of molybdenum may be somewhat 50 above the upper limit of 0.30% to a possible maximum of 1%. The alloy should, however, in every case contain at least 0.15% molybdenum.

The percentage of carbon in the iron or steel must in no-case be greater than about 0.10%, and the nearer the percentage of carbon is to zero, the

The"

better will'be the result. The percentage of manganese in the alloy should not be above about 0.20%, and the less manganese below this upper limit, that is, the nearer the amount of..manganese approaches zero, the better will be the re- 5 sult.

The percentages of phosphorus and of sulphur should be low. While there is no definite upper limit for either of .these two elements,the best quality will be obtained when the phosphorus is 10 not over 0.03% and the sulphur is not over The alloy may be made and sold as a rimmed grade but is preferably made as free as possible of oxygen by deoxidizing in .a furnace so that a 15 uniform deoxidation may be accomplished under suitable conditions in an open hearth furnace or, preferably, in an electric furnace.

The metal is cast into ingots and the ingots are rolled to blooms at a temperature interval of 2600,F., to 2200 F. The rolled bloom product is cooled and equalized at 2000 F., and converted to,billets at a finishing temperature of 1750 F. The rerolling of the billets to final round bars is performed in an interval between 2000 F., and a finishing temperature of 1680 F. After the alloy has been rolled to rods, the latter are cut to an appropriate length and the ends heated and upset to form the enlarged squared length and the end tubular length for receiving screw threads. 3

These ends are then normalized by heating to a temperature of about 1600 F., for 45 minutesand permitted to cool in the air. I

The sucker rods may then be hardened and straightened by the process described in my copending application Serial No. 639,929, now Pat- .ent No. 2,049,830. For this purpose the rods are reheated to a temperature of about 1650 F., andthen quenched in cold water to harden them.

During this quenching, the tubes or other articles will become distorted or warped, even though they may be held to prevent excessive distortion such as would interfere with subsequent handling.

The rods are then reheated to draw the hardness or to temper them. For this purpose they are preferably heated to a temperature of 1200 F., although this temperature may be in some cases as low as 1000 'F., or as high as 1400" F. When the rods have been brought to the tempering 5o temperature they are stretched beyond their yield point as described in the above co-pending application. This straightens the rods and removes any warping or distortion. Thereafter the rods are permitted to cool to atmospheric temperature.

may then be accomplished.

Sucker rods formed of the above alloy as described above have a hardness and elastic limit materially above those of pure, corrosion resistant iron, but have a resistance to corrosion greater than that of steel containing a higher percentage of carbon. The alloy has the very desirable property that it is highly resistant to the action of hydrogen sulphide and saline waters when subjected to alternate or recurrent stresses such as sucker rods are subjected to in pumping a well. Y

Whereas hardened steels and even wrought iron are rapidly attacked by such corrosive compounds under the alternating"stretching and release of successive pump strokes, sucker rods made in accordance with this invention are highly resistant to these corrosive materials and may have a life from 40% to 80% longer than that of wrought iron or steel.

A table of properties typical of my applied to sucker rods and alloy as similar apparatus is same conditions, ran to only 700,000 cycles before failure. A 3% the same con failure.

While my invention has been described with nickel wrought iron, tested/under tions, ran only 850,000 cycles to particular reference to sucker rods for which it is particularly applicable and advantageous, it will be understood that it may be used for other pumping equipment such as pump fittings, tubing, etc., and may be employed for the construction of various other equipment in which resistance to corrosion coupled with strength and hardnesspis desired. Y

What I-claim isi 1. IL sucker rod comprised of low carbon nickelmolybdenum steel, said steel consisting of between 2 and 5%. nickel, between .15 to 1% molybdenum, less than .10% carbon, less than 20% manganese, the said steel being substantially free from oxygen, phosphorus and sulphur.

2. The method of hardening a sucker rod com- .prised of' low carbon nickel-molybdenum steel having the composition specified in claim 1, which as follows: comprises heating the rod to temperatures'ap Typical physical properties secured from made "8 steel after various heat a treatments Yield point Tensile 2 Red. Bmmu Izod im- Endurance All tests made on rounds (drop of) strength oi hardness pact it. limit in air (beam) lbs./sq.in. round area lbs. lbs/sq. in.

lbs.,sq.|n.

. Per- Natural or as rolled condition Puma-cent (finish rolling above 1900 F) 44, 800 65, 150 43 75 134 ormalized and air cooled irom 1650" F 48, 500 06.1!)0 42 79 133 quenched in cold water irom I 1650 F. Drawn-back or tempered to 1200 F 63,250 72, 250 163 93 52, 000 Quencbed in cold water from I 1650 F. Drawn-back or tempered at 1400 F. 56,000 08,000 80 153 85 tating beam to reversed stresses or A test piece of the alloy was subjected as a ro- 30,000 lbs. per square inch computed outer fibre stress at the rate of 36 R. P. M. while surrounded by well water and hydrogen sulphide, air being excluded. It ran to 1,260,000 R. P. M. before failure. A .50 carbon steel normalized, quenched and drawn to 250 Brinell hardness and having a tensilestrength of 115,000 lbs. per

square'inch, tested under the.

proximating 1650 F., quenching the heated rod in water, reheating the quenched rod to temperatures-within the range 1000 F. to 1200 F. to

temper the rod and during the tempering heat treatment subjecting the rod to tensile stresses adapted to stretch the rod beyond its elastic limit, and thereafter cooling the stretched and tempered rod to atmospheric temperatures.

FRANK B. BAYLESS.