code: public static Duration standardHours(long hours) {
          if (hours == 0) {
              return ZERO;
          }
          return new Duration(FieldUtils.safeMultiply(hours, DateTimeConstants.MILLIS_PER_HOUR));
      }
docs: Create a duration with the specified number of hours assuming that
  there are the standard number of milliseconds in an hour.
  <p>
  This method assumes that there are 60 minutes in an hour,
  60 seconds in a minute and 1000 milliseconds in a second.
  All currently supplied chronologies use this definition.
  <p>
  A Duration is a representation of an amount of time. If you want to express
  the concept of 'hours' you should consider using the {@link Hours} class.
  
  @param hours  the number of standard hours in this duration
  @return the duration, never null
  @throws ArithmeticException if the hours value is too large
  @since 1.6