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Abrasion:

 External damage to a hose assembly caused by its  

being rubbed on a foreign object.

Ambient or Atmospheric Conditions: 

The surrounding  

conditions, such as temperature, pressure and corrosion,  

to which a hose assembly is exposed.

Amplitude of Vibration and/or Lateral Movement: 

The  

distance a hose assembly deflects laterally to one side from 

its normal position, when this deflection occurs on both 

sides of the normal hose centerline.

Anchor: 

A restraint applied to a pipeline to control its  

motion caused by thermal growth.

Annular: 

Refers to the convolutions on a hose that are a 

series of complete circles or rings located at right angle to 

the longitudinal axis of the hose (sometimes referred to as 

bellows).

Application: 

The service conditions that determine how a 

metal hose assembly will be used.

Armor or Casing: 

Flexible interlocked tubing placed over the 

entire length or in short lengths at the end of a metal hose to 

protect it from physical damage and to limit the bending radius.

Attachment:

 The method of fixing end fittings to flexible metal 

hose – welding, brazing, soldering, swaging or mechanical.

Axial Movement:

 Compression or elongation of the hose along its 

longitudinal axis.

Basket Weave:

 A braid pattern in which the strands of wire 

alternately cross over and under two braid bands (two over –  

two under).

Bend Radius:

 The radius of a bend measured to the hose  

centerline.

Braid:

 A flexible wire sheath surrounding a metal hose that 

prevents the hose from elongation due to internal pressure. Braid 

is composed of a number of wires wrapped helically around the 

hose while at the same time going under and over each other in 

a basket-weave fashion.

Braid Angle:

 The acute angle formed by the braid strands and the 

axis of the hose.

Braid Construction: 

Term applies to description of braid, i.e., 36 x 

8 x .014, 304L SS.
36 = number of carriers or bands in a braid
8 = number of wires on each carrier
.014 = wire diameter in inches 
304L = material, Type 304L stainless steel

 

Braid Sleeve, Braid Band or Ferrule:

 A ring made from tube or 

metal strip placed over the ends of a braided hose to contain the 

braid wires for attachment of fittings.

 

Braid Wear: 

Motion between the braid and corrugated hose which 

normally causes wear on the O.D. of hose.

Braided Braid:

 In this braid, the strands of wire on each carrier of 

the braiding machine are braided together, and then braided in 

normal fashion, hence the term braided braid.

Brazing:

 A process of joining metals using a non-ferrous filler 

metal, which melts above 800°F, yet less than the melting of the 

“parent metals” to be joined.

 

Butt Weld: 

A process in which the edges or ends of metal sections 

are butted together and joined by welding.

Casing:

 (See definition under Armor)

Controlled Flexing:

 Controlled flexing occurs when the hose is 

being flexed regularly, as in connections to moving components. 

Examples: Platen presses, thermal growth in pipe work.

Convolution: 

The annular or helical flexing member in corrugated 

or strip wound hose.

Corrosion: 

The chemical or electro-chemical attack of a media 

upon a hose assembly.

Cycle-Motion: 

The movement from normal to extreme position 

and return.

Developed Length: 

The length of a hose plus fitting (overall) 

required to meet the conditions of a specific application.

Diamond Weave:

 A braid pattern in which the strands alternately 

cross over one and under one of the strands (one over – one 

under). Also known as plain weave.

Dye Penetrant Inspection or Test: 

A method for detecting surface 

irregularities, such as cracks, voids, porosity, etc. The surface to 

be checked is coated with a red dye that will penetrate existing 

defects. Dye is removed from surface and a white developer is  

applied. If there is a defect in the surface being checked, the red 

dye remaining in it causes the white developer to be stained, 

thereby locating the defective area.

Displacement:

 The amount of motion applied to a hose defined 

as inches for parallel offset and degrees for radial misalignment.

Dog-Leg Assembly:

 Two hose assemblies joined by a  

common elbow.

Duplex Assembly:

 An assembly consisting of two hose assemblies 

– one inside the other – and connected at the ends.

Effective Thrust Area – Hose and Bellows: 

The cross-sectional 

area described by the outside diameter (at the tops of the 

convolutions) less two times the metal thickness of the hose or 

bellows.

Elastic (Intermittent Flexure):

 The smallest radius that a given 

hose can be bent to without permanent deformation of the metal 

in its flexing members (convolutions or corrugations).

Erosion:

 The wearing away of the inside convolutions of a hose 

caused by the flow of the media conveyed, such as wet steam, 

abrasive particles, etc.

 

Glossary

Exposed Length: 

The amount of active (exposed) hose in an  

assembly. Does not include the length of fittings and ferrules.

Fatigue:

 Failure of the metal structure associated with, or due to, 

the flexing of metal hose or bellows.

Ferrule: 

(See definition for Braid Sleeve)

Fitting: 

A loose term applied to the nipple, flange, union, etc., 

attached to the end of a metal hose.

Flat Braid:

 Has a braid angle greater than 45° (See Braid Angle).

Flow Rate:

 Pertains to a volume of media being conveyed in a 

given time period, e.g., cubic feet per hour, pounds per second, 

gallons per minute, etc.

Frequency:

 The rate of vibration or flexure of a hose in a given 

time period, e.g., cycles per second (CPS), cycles per minute 

(CPM), cycles per day (CPD), etc.

Galvanic Corrosion:

 Corrosion that occurs on the less noble of 

two dissimilar metals in direct contact with each other in an 

electrolyte, e.g., water, sodium chloride in solution, sulphuric  

acid, etc.

Guide (For Piping): 

A device that supports a pipe radially in all 

directions, but allows free longitudinal movement.

Hardware:

 A loose term used to describe parts of a hose 

assembly other than the hose and braid, e.g., fittings, collars, 

valves, etc.

Helical: 

Used to described a type of corrugated hose having one 

continuous convolution resembling a screw thread.

Helical Wire Armor:

 To provide additional protection against 

abrasion under rough operating conditions, metal hoses can be 

supplied with an external round or oval section wire spiral.

Inside Diameter: 

This refers to the free cross section of the hose 

and (in most cases) is identical to the nominal diameter.

Installation:

 Referring to the installed geometry of a  

hose assembly.

Interlocked Hose:

 Formed from profiled strip and wound into 

flexible metal tubing with no subsequent welding, brazing, or 

soldering. May be made pressure-tight by winding in strands of 

packing.

Intermittent Bend Radius:

 The designation for a radius used for 

non-continuous operation. Usually an elastic radius.

Lap Weld (LW):

 Type of weld in which the ends or edges of the 

metal overlap each other and are welded together.

Liner: 

Flexible sleeve used to line the I.D. of hose when the 

velocity of gaseous media is in excess of 180 ft. per second.

Loop Installation: 

The assembly is installed in a loop or “U” 

shape, and is most often used when frequent and/or large 

amounts of motion are involved.

Mechanical Fitting or Reusable Fitting:

 A fitting not permanently 

attached to a hose which can be disassembled andused again.

Medium (Singular)/Media (Plural): 

The substance(s) being 

conveyed through a piping system.

Minimum Bend Radius:

 The smallest radius to which a hose 

can be bent without suffering permanent deformation of its 

convolutions.

Misalignment:

 A condition in which two points, intended to be 

connected, will not mate due to their being laterally out of line 

with each other.

Nominal Diameter:

 A term used to define the dimensions of a 

component. It indicates the approximate inside diameter.

Offset – Lateral, Parallel, & Shear: 

The amount that the ends of a 

hose assembly are displaced laterally in relation to each other as 

the result of connecting two misaligned terminations in a piping 

system, or intermittent flexure required in a hose application.

 

Operating Conditions:

 The pressure, temperature, motion, media, 

and environment that a hose assembly is subjected to.

Outside Diameter: 

This refers to the external diameter of a metal 

hose, measured from the top of the corrugation or braiding.

Penetration (Weld): 

The percentage of wall thickness of the two 

parts to be joined that is fused into the weld pool in making a 

joint. Our standard for penetration of the weld is 100 percent, in 

which the weld goes completely through the parent metal of the 

parts to be joined and is visible on the opposite side from which 

the weld was made.

Percent Of Braid Coverage:

 The percent of the surface area of a 

hose that is covered by braid.

Permanent Bend: 

A short radius bend in a hose assembly used to 

compensate for misalignment of rigid piping, or where the hose 

is used as an elbow. Hose so installed may be subjected to minor 

and/or infrequent vibration or movement.

Pipe Gap:

 The open space between adjacent ends of two pipes in 

which a hose assembly may be installed.

Pitch: 

The distance between the two peaks of  

adjacent corrugation.

Ply, Plies: 

The number of individual thicknesses of metal used in 

the construction of the wall of a corrugated hose.

Pressure:

 Usually expressed in pounds per square inch (PSI) and, 

depending on service conditions, may be applied internally or 

externally to a hose.

a. Absolute Pressure

 – A total pressure measurement system in 

which atmospheric pressure (at sea level) is added to the gage 

pressure, and is expressed as PSIA.

b. Atmospheric Pressure

– The pressure of the atmosphere at sea 

level which is 14.7 PSI, or 29.92 inches of mercury.

c. Burst Pressure

 

(Actual And Rated)

 

1.  Actual

 – Failure of the hose determined by the 

laboratory test in which the braid fails in tensile, 

or the hose ruptures, or both, due to the internal 

pressure applied. This test is usually conducted at 

room temperature with the assembly in a straight 

line, but for special applications, can be conducted at 

elevated temperatures and various configurations.

 

2.  Rated

 

– A burst value which may be theoretical, or a 

percentage of the actual burst pressure developed 

by laboratory test. It is expected that, infrequently, 

due to manufacturing limitations, an assembly may 

burst at this pressure, but would most often burst at a 

pressure greater than this.

d. Deformation Pressure (Collapse)

 – The pressure at which the 

corrugations of a hose are permanently deformed due  

to fluid pressure applied internally, or, in special  

applications, externally.

e. Feet of Water or Head Pressure

 – Often used to express system 

pressure in terms of water column height. A column of water 1 

ft. high exerts a .434 PSI pressure at its base.