M A Y 20, 1936
Tubing Specialties
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LTHOUGH we h a v e h e a r d a great deal in recent years a b o u t t h e modern development in cold working of various classes of steel, very little h a s been written on cold-drawn t u b i n g processes. A visit t o t h e SummeriU Tubing Co., Bridgeport, Pa., indicates t h a t t h e technic of finishing cold-drawn tubing has k e p t pace with other lines of metal working. T h i s applies, not only t o many intricate special shapes, b u t t o a wide variety of alloys in practically all metals; in tact, a n y metal which can be satisfactorily cold worked is suitable for finishing into seamless cold-drawn tubing. Possibly one of t h e most marked improvements visible in t h e SummeriU plant is t h e finish which is now produced in seamless tubing. Surface finishes compare favorably with m a n y cold-roUed fiat steel products. Standard size tolerances are much closer t h a n formerly furnished and on a great deal of special work, particularly on smaller sizes, are regularly produced t o a total of 0.002 inch, sometimes, on very small sizes, t o 0.0005 inch. Of course, greater accuracy goes hand in hand with t h e improved finish as m a d e possible b y special processing methods, combined with greatly improved dies. T h e Summerill mill probably has more tungsten carbide and diamond dies in a wider range of sizes t h a n any other tubing mill in t h e country. Of growing importance for many uses is t h e improvement in ductility, seamless tubing now being available in a wide range of sizes with a ductility approaching t h a t of copper. This availability in t h e softer tempers has m a d e seamless steel t u b i n g useful, not only in mechanical applications where bending a n d forming a r e essential, b u t with t h e rapid growth of air-conditioning and refrigeration steel tubing can now be used, adding greater s t r e n g t h and u n d e r certain conditions is more suitable t h a n copper. F o r m a n y applications where great hardness is required SummeriU is regularly producing a wide range of sizes from numerous alloys permitting heat t r e a t m e n t t o so-called glass-hard finish. A few such uses are for watch parts, thread guides, and perforating dies. Variety of Materials Even though t h e big production b y Summerill is still in what is referred t o a s t h e low and medium carbon grades, t h e development a n d use of m a n y aUoys have grown t o t h e point where t h e range of productions covers nearly 50 different grades of material. T h e carbon range is available from what is known a s S A E 1010 grade, containing approximately 0.10 per cent carbon, up t o those having 1.00 per cent carbon. T h e alloy range covers t h e more popular SAE grades—chrome-molybden u m , nickel, straight chrome, a n d t h e so-called 18-8 stainless steel. SummeriU also produces for t h e radio industry a n d other special applications small t u b i n g from pure nickel, a s weU a s numerous grades of nickel-silver, monel metal, etc. Although chrome-molybdenum in t h e 4130-X grade was originally developed for aircraft construction and still is prominent for this use, this grade a n d others in t h e chrome-molybdenum range have proved their merits so definitely for m a n y other purposes t h a t t h i s t y p e of alloy is now second only to t h e low carbon grades in volume production. I t has excellent coldworking properties: very high physical properties, obtained by normalizing. I t s air-nardening properties are, of course, essential in making it so satisfactory for
NEWS EDITION use in welding t u b u l a r structures. I n addition, its high endurance limit makes i t t h e ideal material where high resistance t o fatigue is a factor in performance. Composite Tubing Composite tubing is finding m a n y new applications where it is desired t o combine t h e strength of steel with t h e corrosionresistant properties of non-ferrous metals or so-called stainless steels. T w o or more tubes of different metals a r e drawn t o gether through a die, over a mandrel, effecting a n extremely strong, closeadhering bond.
203 a n d the cost of permitting corrosion t o occur m u s t decide each problem e n c o u n tered. I n making t h i s balance, consideration of a composite t u b e with a n inexpensive body a n d a corrosion-resisting lining (or outer shell) is n o t t o be overlooked.
Patents P a t e n t for Electric L i g h t B u l b with Interior Frosting Held Valid P a u l D . B o o n e , 2707 W o o d l e y R o a d , N. W., W a s h i n g t o n , D. C. IPKIN in p a t e n t 1,087,510 granted in 1928 had claimed an electric light bulb, t h e interior of which was characterized b y t h e presence of rounded, a s distinguished from sharp, angular crevices to s u c h a n extent t h a t t h e resistance t o breakage b y impact was greater t h a n 2 0 t o 45 p e r cent of t h a t of t h e clear bulb. His m e t h o d of achieving t h i s , as s e t forth in the p a t e n t , was t o subject t h e bulbs frosted in t h e usual m a n n e r t o a further etching t r e a t m e n t with a weaker hydrofluoric acid, a t reduced t e m p e r a t u r e a n d for a shorter period of t i m e . T h i s rounded o u t t h e s h a r p crevices, with the result t h a t cracks did not s t a r t therefrom as previously. T h e patent contained tables of comparative t e s t s . T h e Appellate C o u r t of t h e Sixth Circuit said of t h e Wood patent, which was relied upon by t h e defendant as an anticipation, t h a t t h e concept of Dr. Wood w a s for a method of m a k i n g a light diffusion screen; t h a t the brief mention in one sentence of "frosting t h e bulbs in t h e usual m a n n e r , " where electric light bulbs were mentioned, referred to t h e m e t h o d s in practice— namely, exterior frosting—and t h e testim o n y so indicated. T h e Court held t h e Pipkin p a t e n t valid. T h e suit was between t h e General Klectric Co., t h e plaintiff-appellant, a n d t h e Save Sales Co., appellees. C h a s . Neave, Howson, a n d Anderson represented t h e former; Owen a n d Owen, t h e latter.
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SOME SEAMLESS T C B I N O SHAPES
Sizes Cold-drawn seamless tubing is available in a wide range of sizes u p t o 24-inch outside diameter but Summerill's work in tubing specialties is largely in t h e smaller range a n d with lighter walls. This comp a n y h a s recently produced tubing 0.005 inch outside diameter with 0.0008 inch wall. I t also produces hypodermic needle tubing down to 0 . 0 2 inch outside diameter, from both stainless a n d high carbon steels; nickel tubing for cathode sleeves in radio tubes with walls as thin as 0.0015 inch. Shapes Some idea of t h e variety in shaPes available in seamless tubing is shown in t h e accompanying illustration. New forms a r e being drawn constantly a n d the limit of possible variety has not "been found. W h a t might be termed s t a n d a r d shapes, other t h a n rounds, are regularly produced in a wide range of sizes—streamline, hexagonal, octagonal, squares, rectangles, and ovals. S o m e Uses A list of uses for seamless tubing includes: tubing for aircraft construction; golf shafts a n d fishing rods; hypodermic needles; precision p u m p t u b i n g ; instrument tubing (Bourdon a n d capillary); heat transfer tubing for condensers, evaporators, heat exchangers, a n d refrigeration equipment; Diesel engine fuel injection tubing and many others. T h e problem of the chemical process engineer usually involves serious consideration of pressure a n d corrosion. Cold-drawn seamless tul»es have no line of weakness in their walls, a n d design for pressure is a matter of choosing the right material a n d providing sufficient wall thickness. Corrosion resistance is a matt e r of choosing a suitable alloy from t h e wide variety from which tuBes m a y be d r a w n . An economic balance between t h e cost of t h e corrosion-resisting aUoy
Drinker Respirator Decision THE Circuit Court of Appeals for t h e First Circuit, in the suit of Warren E . Collins Co., Inc., et al. vs. Emerson, has upheld one of the patents on t h e Drinker respirator used so frequently t o maintain respiration artificially in cases of infantile paralysis where paralysis of t h e lung muscles makes it impossible for t h e victim t o breathe normally. There were three patents in suit, all of which had been held invalid o n prior publications b y t h e District Court. On appeal, however, this decision w a s partially reversed a n d the second patent, No. 1,906,453, was held valid and infringed as t o all of the claims in suit b y a unanimous opinion of t h e c o u r t ; t h e third p a t e n t was found invalid by t h e entire c o u r t ; while the court was divided as to the validity of the first patent, t w o judges holding t h e patent invalid and t h e third holding it valid. T h e suit was handled for the plaintiffs by Nelson Littell of H a m m o n d & Littell and for t h e defendants b y Robert L. Thompson of Roberts, C u s h m a n , and Woodberry.
